[lucasban]

Doing a bit of digging online, while there is evidence that /some/ people use it, it appears to be very limited. I understand the desire some people have for an unambiguous English term to refer to things from the US separately from those of the Americas in general, and see the value in doing so. Personally, as a native English speaker, I find USAnian to be clunky - maybe someone has thought (or will think) of a term that feels more natural. It feels analogous to the push from (largely English-speaking) activists in the US to use the term "latinx", much of the intended audience doesn't run into issues with the current terminology and aren't looking for a new term, and the term doesn't feel natural to existing speakers.

[anotherhue]

Are we not allowed say Yanks anymore?

[mh-]

Yank here, you've certainly got my blessing. Can't imagine someone being bothered by it. I think of it as a demonym just like Brits or anything else.

[ASUfool]

Those with deep Confederate roots might be bothered.

Or Red Sox fans.

[SSLy]

Is the term also fine to use when trying to include the BIPOC citizens?

[SR2Z]

All Americans get to be called Yanks, and if the southerners complain, hey - they did lose the civil war.

[lucasban]

You can say what you want, whether or not people will understand what you mean or interpret it the way you intended is the more relevant question, in my opinion.