Part 1

During WWII, the Wehrmacht, as in the total of Army, Navy, and Air Force employed about 500.000 female auxiliaries as so-called Wehrmachtshelferinnen. They mainly worked in communications, anti-air defense, administration and the health services of the Wehrmacht. There are also examples of female pilots being part of the air force, although on a very limited scale. Most famous among them probably, Hanna Reitsch, a test pilot and propaganda icon.

In her much regarded book, Hitler's Furies, historian Wendy Lower approaches the heavily understudied topic of participation of women in Nazi crimes. She writes of approximately half a million women who went to the East as part of Nazi rule and occupation and participated in various Nazi war crimes and crimes against humanity against the native population, Jewish and non-Jewish, of Poland, the USSR and other nations under the iron boot heel of Nazi occupation.

Similarly, a very small number of black Afro-German and African troops did serve in the Wehrmacht, many of them in the "Free Arab Legion", created in 1941. While unable to ascertain if those units had a female auxiliary staff including black women, the idea of one of there being one and potentially picking up a weapon is not totally impossible but very, very unlikely given both the Nazi German attitude towards women and toward black people.

So, as for this specific case: Are there any historic examples of this? No, with a high degree of certainty. Is it plausible in any way? It's not completely impossible that there might have been one case but it also isn't very plausible.

As for:

Female soldiers also feature alongside the allied forces too fighting in the same groups as men.

I have no idea which formations COD WWII will feature but at least in the Soviet or Yugoslavian case or in the case of e.g. the French resistance movement this is far from wrong. Over 800.000 women served in the Red Army, many of them in combat roles, covering things such as snipers, tank drivers, machine gunners, pilots and more and they did so in the same formations as men. There even were female political officers / commissars in the Red Army. And in the Partisan movement, women also took on a variety of crucial roles both in the Soviet Union as well as in Yugoslavia where about one sixth of all Partisan forces were female. In both the French and Italian resistance women represented between 15 to 20% of all members of these forces, which in the French case also extended to North African and African women. So, historically speaking both women fighting as well as even women fighting in the same formations as men can be considered a mass phenomenon in WWII that included hundreds of thousands of women fighting for the liberation of Europe from Nazi Germany, often closely together with men.

But let's talk about COD WWII as a piece of historical media and it's potential criticism on that front. And I want to start with:

Honestly to me this screams inclusiveness and political correctness and in a way works to somehow make the nazis seem less evil and inclusive.

I think when contextualizing the kind of historical media that COD WII is, this sort of criticism rings... a bit shallow, I am sorry to say. Mainly because there is good reason to extend the same argument to the multiplayer of all WWII COD games and the WWII titles in the franchise as a whole. I mean, think about it, WWII titles in COD all enable the player to take over the role of Wehrmacht soldiers, members of an organization that was so deeply and heavily implicated in war crimes and crimes against humanity that it makes one recoil in horror.

I have written several answers on this very subject numerous times and historically speaking it is no exaggeration that during the war and especially after 1941 every member of the Wehrmacht was acutely aware of the crimes committed by this organization and that, using the results of Christopher Browning's Ordinary Men, while impossible to indicate an accurate percentage, we can theorize that about 80% of its members did participate in these crimes directly.

And every piece of WWII video game media with a multiplayer lets you as a player experience being a Wehrmacht soldier without any of this rather important historical context, mostly completely and knowingly avoiding it. It basically puts you in the shoes of a generic historical person, who by all accounts was extremely likely to have committed grave and brutal crimes. And even if, as was reported, the single player plans to tackle the issue of the Holocaust in the name of telling a narrative and potentially, historical accuracy, that even exacerbates the problem because it creates a rather monstrous ludonarrative dissonance.

What I mean by that is that the way the game is played and the narrative the game presents are in dissonance with each other: The single player campaign, presumably, will include the Holocaust as something American soldiers discovers and which will give some sort of metaphysical meaning and framework for the hardships they endure to fight this war. While this, and I include Band of Brothers as another piece of historical media here, has its own problems – using the Holocaust as a sort of "women in refrigerators" trope –, it gets especially dicey in connection to the multiplayer.

Within the narrative of the single player campaign, the Holocaust is presented as something horrible, as something deplorable, and something that gives a larger metaphysical meaning to the hardship of fighting that war (whether that fits the gameplay experience or if it really fits the narrative at large left aside for a moment). And yet, in the multiplayer, which is the reason most people buy the game, there is no taboo or quarrel about people playing as representation of soldiers who fought to enable a continuation of the Holocaust. In fact, "cool German weapons" is a selling point of the game. So, the single player presents to you a story in which the horrors of the Holocaust serve as a main motivating factor but the multiplayer gives you the option to fight as exactly the people perpetrating the Holocaust.

So, if we want to talk about the Call of Duty franchise and the pointed criticism of normalizing Nazism and making the Nazis seems less evil, especially in connection to its multiplayer, the first issue that needs to be address is the simple fact that by letting you play as a generic representation, an avatar, for group that played a key role in the perpetration of the Holocaust and other historical crimes and instead of penalizing the player in some way celebrates that and makes it a major selling point. If we start with the criticism of historical accuracy of the multiplayer, then the starting point should be that as a German soldiers you don't massacre Jews; don't use Soviet civilians to clear minefields; don't burn down Polish villages; don't force Yugoslav civilians on a death march; don't annihilate entire villages; don't starve Soviet POWs to death in the millions; don't rape and plunder your way throughout all of Europe instituting a policy of systematic oppression, mass murder and genocide. Making the case for historical accuracy in connection to making the Nazis seem more harmless than they really were, must start with this issue because it is the elephant in the room; the glaring problem of accuracy when it comes to WWII video game media and the issue of historical accuracy.

And unlike in movies, it is the only form of media that does this: Putting the individual player/viewer in the shoes of a bunch of murderers without addressing the issue and glorifying that experience. The only movies that do this too are German WWII Landser movies.

But then, one can argue, it is just a game and the multiplayer especially is divorced from historical reality and all about an enjoyable experience of competition within a barely pseudo-historical setting. If that is the view one takes however, the inclusion of black women on the Axis side (as revolting as I personally might find that as I find the general possibility of playing as a Wehrmacht soldier in general), falls into the same framework of it just being a game and being divorced from the historical realities. If it is indeed just a silly piece of entertainment media without any wider contextual implications, nothing stands against this inclusion within the framework of the larger argument and the only reason to criticize this decision comes from a place of having some sort of personal problem with having a black woman as a playable character in a video game. If however, there is real concern for historical accuracy and making the Nazis seem more harmless than the actually were, then there is a much larger issue to address here that takes both historical as well as moral priority over the inclusion of women, black woman or any other player character model on any side of the multiplayer.

A bit of clarification OP if you would be so kind?

I have only seen references to the possibility of having a Black Female German avatar for multiplayer. Are you asking just about the possible historical foundation of such a combination at all given it's inclusion in any capacity? Or have they teased a character like that showing up in the campaign?