Puberty blockers, which are mostly what Republican legislation is focusing on right now, don't do anything to children's genitals. They simply delay puberty until a teenager is old enough to make their own decisions about hormone therapy. Some 16 and 17 year olds do receive either testosterone or estrogen analogs, in cases where doctors, in consultation with the teens' parents, determine that's for the best.
A handful of trans 16 and 17 year olds in the US have received mastectomies, but that practice is very rare because surgeons are highly reluctant to do that sort of procedure on minors. When I say a handful, I mean something like 20 people in the last several years, and the incidence has been decreasing.
All the legislative uproar is much ado about nothing. Lawmakers are acting like some big crisis is happening, when that's not the case at all.
The real crisis is what's happening to trans kids, feeling targeted, rejected, stigmatized, and denied puberty blockers. A great deal of mental anguish is caused when a teenager is forced to go through the wrong puberty. And also, going through the wrong puberty makes transition later, when they're more mature, much more difficult.
Lawmakers really don't know what they're talking about, especially when they talk about genital surgery that doesn't happen anywhere.
They're either doing that to cause false outrage, or they just aren't informed.