Why?
Why should Woman be a matter of identity rather than body type?
It's not like our bodies stop being female, or that being female stops having physical and social consequences, or that the history of what happened to female people because they were female somehow didn't happen.
No one is stopping anyone creating new words for the group of people who feel they have a thing in common that is definitely not actually being female but should for some reason be pretended to be the same thing.
No one is stopping a damn thing at all that trans women and women-who-think-trans-women-are-women may want to do together.
The only thing that we are saying no to is that that group cannot be under the name woman because that is the existing name of a marginalised group with its own stories, experiences and history.
Many female people find the projections of what "woman" means by genderists as offensive as your Chinese group would find someone turning up to join them with a 1970s comedy Chinese accent and the accompanying facial expression.
Because for all your "open to all people who identify / understand themselves to be Chinese, regardless of genetics or identity documents , or whether they look white or black (as many Chinese people may well do), or otherwise" I'm pretty sure your hypothetical Chinese ethnicity groups also have boundaries beyond which they will not stretch the meaning of Chinese.