The defining skeletal differences are mostly in the pelvis, which undergoes much of its development in puberty. Intervention in those years should allow for trans teens to develop along affirming physiological lines, rather than being mutilated by a dysphoric puberty.

Buuuuut I did overstate my case, though; such early treatment is still on the rarer side, so it doesn’t look like there’s definitive answers on how that impacts skeletal development. We can draw conclusions, I think, but the literature is mostly focused on the psychological development rather than looking at physiology.