Me and mine are about to have a baby.
When people ask if it's a boy or a girl, we just say "we don't know yet."
We'll just keep saying that after it's born, until it decides for itself. Until then, he/she/they/it pronouns cus who cares it's a freaking baby, it doesn't have a personality much less a gender.
It's just that easy. My son ID's as trans-masc right now. Doesn't matter to me if it's a phase or not. I'm on board. But either way, you need to clean the cat litter, you little shit.
It's like that bit from The Umbrella Academy:
Five: "Look, Vanya, you stupid bitch, we need to—"
Luther: "Actually it's Viktor now."
Five: "Sorry. Look, Viktor, you stupid prick, we need to—"
(I can't remember who exactly said what in that scene, but I laughed pretty fucking hard at how nonchalant everybody was. GOALS.)