In short: no. The Eyewitness books I can say outright are not scholarly. They may contain a bibliography of scholarly sources, but they aren’t scholarly themselves. The Smithsonian publications are likewise probably going to have some scholarly references or may even be written by academics, but I think they’re unlikely to be considered ‘scholarly’ on their own.

The key to whether something is scholarly or not is whether it’s gone through a ‘peer-review’ process. This means that other experts in the field have examined the text and determined it has been conducted in a way that reflects best practices for that field of study. Usually, this means it’s published by a university press (Yale, Oxford, etc.) or that it comes from a high-quality education press (Palgrave McMillan, does good work for European history, for example).

I don’t know what your resources are or what you have access to, but try getting on a database like JStor if you have access to a library computer. And in general, talk to a librarian, a reference librarian especially, about what scholarly publications they have in their stocks. Journals especially tend to be expensive to subscribe to and have low usage outside of colleges and universities. So they may not subscribe to them. You can also sometimes find individual articles as PDFs online. Try searching for a journal related to your topic of interest (American History Review, for example) and see if they have an online database of their articles.

Good luck!