To start you off, I'd recommend checking out this thread, particularly the comment by /u/Khosikulu.

In brief, Afrocentrist claims about ancient Egypt are not accepted by Egyptologists or mainstream Africanist scholarship.

There have been quite a few scholarly take-downs of the major Afrocentrist talking points.

Stephen Howe's book Afrocentrism; mythical pasts and imagined homes provides an overview of the intellectual history that led to the rise of the Afrocentric school in the 1960s, while debunking a lot of the ideology.

Kwame Anthony Appiah's work "Europe Upside-down; fallacies of the new Afrocentrism" accuses the Afrocentrist school of perpetuating the old Eurocentrist ideas of race, hyperdiffusionism, "western civilization" and merely inverting the lens. That is, accepting essentialist ideas of race (that race is a real biological fact and a driver of behavior) and simply asserting black African primacy in inventing "civilization" (itself a messy concept).

Clarence Walker starts his book We Can't Go Home Again; an Argument about Afrocentrism with these words:

Although some of its advocates may claim that Afrocentrism is history, the methods by which its proponents reach their conclusions are not historically rigorous. The scholars who call themselves Afrocentrists have not written history in the strictest sense of the term; what they have produced is a therapeutic mythology designed to restore the self-esteem of black Americans by creating a past that never was. Concocting for themselves and their followers a mix of historical notions and views, Afrocentrists use a historical style of argument to validate their analysis of the cultural plight of contemporary black Americans.

Ditto, Tunde Adileke's book the Case Against Afrocentrism devotes early chapters to discussing Black American scholars like Martin Delaney and William Garnet of the 1840s and 1850s. These two, in particular, argued for a view that Ancient Egypt was "negroid" and the corresponding prestige of ancient African civilization, as an abolitionist rhetorical weapon against American white supremacist historiography which held that Africa had no history of civilization and therefore enslavement was morally permissible as racial uplift.

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The thing is, Africanist scholarship has greatly expanded and developed over the last 60 years (roughly since 1960). In African Studies, and I think more generally, the old Eurocentric model of "Western Civilization" and disciplinary categorization that tries to separate Egypt from the continent of Africa is no longer accepted. So, Afrocentrism is arguing against a position that is not held by mainstream scholars anymore (although it does linger on in popular culture). Scholars fully accept that Egypt is part of Africa and ancient Egyptian society had deep engagement with Libyan and Nubian peoples.

But, current Egyptology is more interested in trying to interrogate how ancient Egyptians perceived ethnicity and difference with their Libyan, Nubian and Levantine neighbors. For instance, here is a recent article on the topic by Juan Carlos Moreno Garcia.

And of course, there have been great advances in historical DNA demography over the last 30 years. When it comes to DNA of Egyptian mummies, the results are consistently that the population of Ancient Egypt was genetically similar to the modern population. One recent discovery is that sub-Saharan African genome frequencies increase after the Roman period.

So, DNA testing strongly indicates that modern Egyptians are the descendants of ancient Egyptians. Which debunks claims by Cheikh Anta Diop or Yoseph ben Jochannan that ancient Egyptians were "Bantu" or "Negroid" and that there was a large scale population replacement in the sixth-seventh centuries because of the Arab conquest of Egypt.

Cheikh Anta Diop claimed to have invented a melanin detector with which to test the skin pigmentation of mummies. He claimed that the results supported his claim that Egyptian pharaohs were dark skinned. However, I can't find any references to any mainstream Egyptologist using this "melanin detector" and I suspect it is treated as pseudo-science.

So I tried a search of the literature and was surprised at how little I could pull up using the keyword "hotep" in various different combinations and iterations. I really couldn't get a single article that spoke specifically to the current cultural notion of "hoteps," which I take to refer to a largely internet-based community of ultra Black-nationalists who have adopted hermeneutics, ontologies, epistemologies, mythologies, etc. that center and exclusively prefer Blackness. Obviously, that's a crude definition to get at a complex net of phenomena.

While I cannot therefore speak specifically to what I think of when I think of "hotep" (i.e. a contemporary movement, which would be at least substantively outside the date parameters of the sub anyway, but which can be studied using historical methods), I can speak to related groups and concepts that gave birth to my own definition of Hotep-ism.

So, the 20th century brings quite a few religious groups that have afro- and Black-centrist ideologies: Nation of Islam, Moorish Science Temple, and Nation of Gods and Earths/Five-Percenters. A common thread in these is an attachment to Islam and/or the Middle East: Islam provided a mode for religious expression that Black Americans felt they could identify as more "purely" Black and free from white/European control. Concomitantly, you start to have major pushes to label Christianity as a slave religion: narratives paint Christianity as a tool the white man used to keep the Black man in a state of willing servitude, as something that was once Black but stolen by the white man and perverted, or an outright tool of the devil. Obviously these claims varied in their severity, but they are very much taken up in the zeitgeist by disaffected Black Americans facing a situation not entirely different from that of their great grandparents: recently freed sharecroppers were kept in a state of economic bondage and faced constant threats of physical harm, including lynching, and were deprived their rights as a matter of course. Mid-20th century Black Americans looked around and saw themselves held in a state of economic bondage where they were constantly held at subsistence levels, including being precluded from that great ideal of American economic mobility, home ownership. They were also routinely lynched, beaten, thrown in jail and convicted unjustly, etc. So the notion that anything associated with whiteness was suspect as part of the systems of oppression that kept Black Americans unequal should not be at all surprising.

These groups developed various cosmologies and accompanying mythologies to account for the current state of the world, often writing accounts of history that were bottom-up (written from the perspective of the oppressed). It is important to note here that from (especially) a religious studies or even a historiographical perspective, calling these beliefs "mythologies" and "cosmologies" has nothing to do with a truth or value judgment: the notion that the cosmology developed by the MST or the NGE is any different substantively from that of Christianity or more orthodox forms of Islam, to name just a few, is not only problematic but just wrong. Indeed, Christianity, Islam, and everything people associate with the idea "religion" has its own mythologies that account for phenomena, states, etc.

Which gets in a way to your major question: scholarship, especially historical scholarship within religious studies, does not ask truth-claim questions about these sorts of things within the context of studying those groups. It is not helpful for understanding the NOI, the time period they were in, or the phenomena that gave rise to them to question whether their cosmology is "objectively" historical. What we can (and arguably ought to) do is catalog those claims and ask the questions of why they arose, how they fit with each other, how they compare to the broader society's claims, etc.

Understanding this has uncovered the immense role unorthodox Muslim new religious movements have played in the American rap and hip-hop movement, for example. A fine-tooth comb pulled over the lyrics of rap songs from the 80s and 90s even up to today reveals enormous influence from NOI and NGE especially, but also more "orthodox" (Sunni or Shia) Islam and even Christianity.

What this should not be taken to mean, however, is that historiography is not interested in the truth about the past (although metahistory right now has a lot to say about the very idea): there are trends within historiography that account for Ancient Egypt, for example, and a hotep account will be held against the scrutiny of what the scholarship broadly agrees upon. So where Hotepism substitutes its own versions of history that are blatantly ahistorical, Hotepism becomes not legitimate history but an object of historical study itself: we don't learn more about Ancient Egypt from Hoteps, we learn more about present-day America from Hoteps.

As a final note, just from personal experience in courses focused on Black America and even those that simply devoted some measure of focus to Black Studies, I can tell you that I've had two men who expressed hotep views in classes I was in in undergrad. One time I remember clearly, a student made a comment about how "homosexuality didn't exist in Africa before Europeans brought it there," an oft-repeated and quite old hotep claim. Within the context of the class, the professor politely corrected him on how false that is. Which gets to the difference between describing a historical group's beliefs and confronting misinformation in scholarship and education: just because it is not our job to prove or disprove the beliefs of our subjects when we discuss them, scholarship is held to a different standard, i.e. peer review on scholarship that made claims about homosexuality being non-existent in Africa before the arrival of Europeans would be wholly unforgiving.