Although he doesn't believe you can change sex he did want to change his body to help him feel "right" in himself.
Oh blimey, that's quite a lot of surgery - that must've been really hard going. Hope he's all good and healthy now. I guess then he doesn't go along with the current gender ideology thinking that gender is innate and separate from sex as for your son it seems very much tied in with the body and feeling that it's the body that is wrong.
Admittedly this is what I thought being trans was about originally (gender dysphoria related to the body) before all the stuff about accepting people as innately women who are very outwardly male looking and vice versa. But some people get called transphobic when they say that bodies and genders are meant to "match". Would you say this is a common view among your child's peers ? Or would they take the view that a very feminine looking natal female could be just as male as, say, Daniel Craig, because it is purely down to their internal gender identity?
Do you believe that a person needs to at least have gender dysphoria to be trans or can anyone identify as trans regardless of their gender expression etc?
You said your daughter is non-binary - how do you feel about this? You have referred to them as 'she' so I assume you forget they don't have a gender? (I would too, we are so used to pronouns referring to actual sex, it's like re-learning language).
I note you say 'boy stuff' - do you believe some activities etc are "for boys" and some for girls? Do you think this has in any way affected your child's attitude towards gender stereotypes?
Can you say any more about how he identified that he was a boy/man? This is the part I really struggle with - to me, "boy" etc literally only means you have a male body. Yet clearly for him it means a LOT more. Are you able to expand on that at all?