The debate about trans rights in public policy would be very different if it were about giving newly hatched clownfish access to women's restrooms.
Kinda think you're missing the point, intentionally or not, although there seems to be a great many people in the same boat. As I've pointed out several times, philosopher of science Paul Griffiths quite reasonably argues that "The biological definition of sex wasn’t designed to ensure fair sporting competition, or to settle disputes about access to healthcare":
https://aeon.co/essays/the-existence-of-biological-sex-is-no-constraint-on-human-diversity
Given those biological definitions, it is simply irrelevant to the question of "access to women's restrooms" whether all of the "vagina-havers" qualify as (biological) females or not. The only issue is whether those using those facilities are, in fact, "vagina-havers". Similarly with women's sports, though the criterion there is basically XX-karyotypes: "no XY need apply".
However, the waters are muddied by endless, and by endlessly and pointlessly enervating squabbles over the definitions for the sexes. For instance, I see someone linked to an oldish post by Jerry Coyne on his Why Evolution Is True blog about an article by one "Ash Zemenick" on "Sex and gender are binaries? Sorry, that's a scientific falsehood":
https://whyevolutionistrue.com/2023/06/04/sf-chronicle-sex-and-gender-are-not-binaries/
However, neither Coyne nor Zemenick nor a whole raft of other so-called biologists seem to have a flaming clue that any number of reputable biological journals, encyclopedias, and dictionaries STIPULATE that to have a sex is to have functional gonads of either of two types, those with neither being, ipso facto, sexless:
https://academic.oup.com/molehr/article/20/12/1161/1062990 (see the Glossary)
https://link.springer.com/referenceworkentry/10.1007/978-3-319-16999-6_3063-1
https://web.archive.org/web/20181020204521/https://en.oxforddictionaries.com/definition/female
https://web.archive.org/web/20190608135422/https://en.oxforddictionaries.com/definition/male
https://twitter.com/pwkilleen/status/1039879009407037441 (Oxford Dictionary of Biology)
Zemenick, somewhat reasonably, argues that the "gametic definitions" for the sexes means that:
As you can see, some people, for these reasons, don’t produce or have gametes at all. Therefore, there are three states: no gametes, eggs or sperm. It’s a triplet, a trifecta. Gametic sex is not binary.
Yes, there are "three states", but only two of those qualify as sexes, the "no gametes" qualifying as "sexless" -- hardly a sex. Like saying "religion-less" is a religion. So he "concludes", erroneously, that that means that sex is not a binary. But there's diddly-squat in the biological definitions that justifies concluding that everyone has to have a sex. Which Griffiths emphasizes in that article of his right out of the chute:
Yes, there are just two biological sexes. No, this doesn’t mean every living thing is either one or the other.
But Coyne, rather cluelessly, insists on his own rather idiosyncratic definitions for the sexes -- probably because he balks at "sexless" -- that are flatly contradicted by the standard biological definitions:
The definition above involves having a developmental system evolved to produce eggs and sperm, not whether it actually does so.
Absolutely diddly-squat in any of those biological definitions about "having a developmental system evolved to produce eggs and sperm." Someone might ask him to put his money where his mouth is and cite some credible sources saying that. Gawd knows I've tried on his blog and been banned for my troubles -- classy fellow ...
So you and Coyne and Zemenick and all their ilk can all die mad that reputable biologists have so stipulated, but that will not -- in any way, shape, or form -- change those definitions. They ARE what reputable biologists use as a common frame of reference; it is how they are able to compare many different anisogamous species.
You can use other definitions for the sexes, but then they ain't biology and you're engaging in science denial. Hardly better than Zemenick and the rest of the transactivists and their useful/useless idiots.
If y'all are really serious about resolving the transgender "contretemps" then it seems the only way off the horns of a serious social dilemma is to endorse those biological definitions and then use other criteria for adjudicating access to sports and toilets.