We've done this over and over.
Additional provision is fine, but I don't see how that can be compulsory other than in new buildings. There will be very many premises who don't have the space or plumbing to offer three lots of facilities (plus, potentially, disabled and baby-changing provision).
I have no objection to extra provision where it is logistically possible (but I do object to the opt-out being to colonise the existing Ladies'), but am confused about who would use what.
If (as I believe would be the case), the vast majority of women prefer the pleasanter smell and the safety of a traditional Ladies', and the only people 'presenting as' women who use the GN ones are trans, why can't they use the Gents' in the first place, as they will stand out by going into the GN ones.
If the answer is that it is not safe for those who are not 'male identifying' men to be around men when they are vulnerable, why are women expected to do so now?
There is also the issue of transmen using facilities with male-bodied men who know that the transmen are female-bodied. Will that not put them at risk, too?
In schools, where the sexes are developing differently and both are coming to terms with puberty and sexuality, there is (to me) no good reason why girls should have to deal with periods in front of boys, or boys should have to wee in front of giggling girls. Even single-sex facilities (showers as well as loos) can be embarrassing at that age.