I have been chatting about this over the last couple of days. I’m not an expert so this is open discussion.
In the US, trans rights are, by my reading, entirely bound up with sex-based rights. US trans people have no dedicated set of rights.
This is not the case in the UK. Trans people have a dedicated category (gender reassignment) in our equality legislation.
Does that make sense?
In the UK, a trans person cannot legally be fired for being trans, or refused healthcare for being trans, etc. Those rights are not contingent on sex.