Seriously, the girl's sports thing has revealed how many people, including liberals, don't think trans people are valid. If you're talking about "biological boys" or "biological males," you clearly don't get it and are probably just a transphobe. Because there are answers to your questions, they've been given repeatedly, if you care, which you don't.
I don't personally care about sports but I understand it's an easy wedge issue. If people concede trans girls, even those who've never experienced male puberty, should not be playing sports with other girls then they believe we're not really girls and women and will agree to exclude us from all such spaces. Which is what Democrats are gearing up to help Republicans do right now.
And of course, trans men and trans masc people don't come up in these conversations at all.
@lulu @gwynnion One problem currently with abandoning gender-separated sports is that there's a lot of money involved, e.g. without women's sports there's a ton of athletic scholarship funds that would, as a practical matter, only be available to men; this would be highly regressive in practice. (e.g. Title 9-related issues in the US.) Similarly for pro sports; the situation as-is is already pretty regressive, this would make it far worse.