i recommend practicing pronouns and terms of relation, thats the biggest thing from my perspective. just listen to what they tell you and believe it.

coming out to people is hard, but in my experience the sooner you feel comfortable telling people close to you the easier it is to start telling anyone. not recommending you encourage coming out, but being there to provide positivity and validation about their feelings is huge.

The only hesitation I’d give with this advice is, it may be better to wait on pronouns until they’re more fully out. It sounds like they have family they are NOT ready to know, and… Well, you can brush off one or two misgenderings without much suspicion, but eventually it could leak some information they don’t want out yet.

I had a friend in a similar situation, out to close people, but not out to their family or strangers. We decided it’d be best to keep using he/him, old name, etc. for convenience and safety, until they finally fully came out last year. The only difference from my perspective has been to delay those habits for a bit. No situation is the same, though, and the parent would be beat served talking to the kid.