Ironically, loooong before I realized I was trans, I had a double gynecomastectomy as a 'man'. I didn't even want it; was at a routine physical and the doctor said "Oh, you know we can remove those for you?"
when i was a teen, i first got the idea of reducing my breasts bc i worried about my back. i wish i’d have been able to pursue it (alas, poor), even if i later realized i mostly wanted them gone for Gender Reasons.
Saying children under 18 shouldn't get surgeries unless it is provably required for their health and well being is usually pretty uncontroversial but the issue is when only certain people are completely forbidden surgeries under any circumstances even when they are necessary for wellbeing