Puberty blockers exist and have been studied and used for literal decades for other reasons.
In the case of a trans woman having not went through puberty as a male then yeah true enough as far as I know.
The science says 2-3 years of hormone therapy levels the playing field and there's no more advantage.
Are you sure about that? Because I looked it up and (after a few instances of "we have no idea but maybe not") I found this. I'll also admit that I only read the conclusion so I can't make any guarantees for the quality of the paper.
In fact, women who haven't transitioned often have an advantage because their testosterone levels can be higher than women who have transitioned.
Yeah that's the thing: Testosterone is only one part of athletic ability. The paper lists some parameters that are either not affected or affected but not reduced to within the average range of cis women, but the obvious example would be height.