I know that gay men need to go through surrogacy to have children. But what if this happened: FTM transitions, meets cisgender male, and they want to have kids. Could the FTM have surgery to remove old eggs, or something, since biological females are born with all their eggs inside them, and could those eggs be planted inside a surrogate and inseminated with the partner who was born biologically male? Or are eggs destroyed upon transition?
Well, it depends. I don't have eggs, and I never did, because I'm weird. The average trans guy, though, is different. A trans guy can have ovarian tissue removed prior to taking testosterone, or just after it begins, and the eggs can be implanted in a surrogate, and a baby happens. There is a theoretical, but pathetically small risk of pregnancy in the first couple of years of T, and so I suppose one could also remove ovarian tissue and use a surrogate to make the baby. However, I'm not sure T has a particularly healthy effect on eggs. Lastly, in the first few years, if T is stopped, some guys will be able to get pregnant, and there have been approximately two recorded cases of this happening intentionally, without the guy detransitioning. But eventually, the eggs would be damaged beyond repair, as far as I know, and regardless, a hysterectomy is advised within five years of starting T, which would cut them out, making them nice and useless. P.S, I hate the term FTM. Not attacking you for using it or anything, I understand your intentions were good.
Normally, I do talk with no difference (e.g. if I were talking about you, I'd say "this guy did this" and not "this girl did this" or "this ftm did this.") But yeah, I feel that a guy who was born a guy definitely won't have eggs, so I felt it was necessary.