@MargotBamborough
I'm not just talking about physical spaces, but any "women-only" supports - that includes STEM opportunities targetted at girls, returning to work schemes, social nights, over 60s excercise groups, drop in advice sessions, women's writing prizes - basically anything that exists today because in the past women have said - "hang on, this isn't fair" or "look, men are almost always much better at thing [X] because they get a lot more opportunities and encouragement as kids, so we'll have a women's version where we can progress at our level and find out what we can do" or "you men are stopping us talking about community needs that impact us because they don't interest you, so we'll have a woman's group where our stuff comes first".
The only solution, as far as I can see, is third spaces, and an absolute ban on people using single sex spaces for the opposite sex, regardless of where they are in their transition, whether they have had any surgery, or what their "legal sex" now is.
So far me, this is jumping to a solution without fully defining the problem. I don't mean I expect you to define the problem in your post - I mean society has been pushed into arguing about solutions and skipped a solid definition of the problem. It's all hand-wavy "TWAW so it's just the same problems as women have, except more so because we are extra oppressed, why are you asking you bigot?"
But all the women-only stuff exists as a result of first identifying a problem. For example, before opening up a Women in STEM event to trans women, I'd want evidence that trans women have the same challenges, and indeed that other men don't. I don't want resources that exist to mitigate specific problems having a secondary utilisation to relieve trans women's gender dysphoria, because that's stopping/ reducing their effectiveness in doign what they were set up to do.
So what I want to see is data and clarity about the problems trans women face not just the assumption that provisions shaped by and for female needs are the right ones for them as well.
How do we reconcile the needs of the kindest, gentlest, most harmless trans woman who feels completely unable to use a men's changing space with the needs of a rape survivor whose trauma response to seeing a male bodied person a women's changing room will make her feel completely unable to use it?
Agree likely additional spaces (and let's also ask the question about other men, maybe victims of rape, who may be equally unable) but I think it's for trans people and their allies to define what they need and make the case for it based on first principles for both the need and the shape the solution takes, not simply "the women have it so I should too". And if their solution is "best place for us is in with the women" it's not enough to just base that on getting away from men, they need data to show how their need is the same as that of the women, including the effect of socialisation and childhood decisions, and that the impact of their presence on other women who need that space is the same as that of a female person.