If you don't mind me asking, is there a specific reason that in particular is something that won't be added, or is it just not in your current plans?
Cause if it's the later, I will say that with the way it is now i.e. choosing your character's pronouns as an infant, without any opportunities to change them, it at least to me, heavily implies, if not outright states, that the player character can't be trans.
Like sure the MC is a changeling, but they're seemingly still being put in a body with no real choice in the matter as an infant, so it seems to just be being assigned a gender at birth with extra steps.