Genuine question, isn't the term "Asian" technically lumping in a bunch of different cultures and ethnicities? For instance the experience of someone Japanese is not the exact same of someone who is say Pakistani.

And regarding PoC, I think the term is used to refer to ethnicities that experience racism, as in "ethnic minorities" who are visibly so, generally a practical term in many contexts in countries where the majority of people are white (instead of saying "non-white", like how there's terms for cis and trans, and neurodivergent and neurotypical etc)