I recently proposed this idea on IRC:
Instead of adding X as an option on passports, why not do:
""
That is to say: remove gender markers entirely. Don't do "M/F". Don't do "M/F/X". Instead, do: ""
Nobody gets a legal gender. Your doctor only needs to know what anatomy you have, for medical treatments and such. This would remove a lot of the bureaucratic bloat, and might be nice for intersex people for example.
I'm non-binary myself, but often find pronouns cringe. I'm just Leah. Leah Rowe.