For me and my DC and our friends, this is not about single sex spaces, I think it is a privilege to have that as your focus.
I have been a victim of male violence from age 12 to 23; grooming, sexual abuse, domestic violence, pregnancies and the medical 'care' that came with it. So I'm not speaking from from position of privilege regarding single sex spaces.
What is impacting us is a lobby led by adult males is impacting our daughters. Girls that have been drawn to each other, mainly due to neuro-diversity, some of whom are gay or bisexual. All in some way gender non conforming. Also non conforming in many other aspects.
DD is just the latest in her form group to question her sex. In her form group, there are 2 girls that are now boys and 2 non binary children (girls). These girls are perfect as they are, they are the absolute best kids. There is nothing wrong with them, they are not men, there is nothing at all wrong with the way they are girling/womaning.
I am walking a tightrope of remembering to call Poppy Dexter and Ella Ray (names changed) and trying not to show the fear on my face when DD says she thinks she may not be a girl.
I am so scared of DD being guided down a route that ends with double mastectomy, lifelong hormones, potentially more serious surgery that will impact her physical needs to go to the toilet even.
If you're hypothetically worrying about single sex spaces, or being an ally to trans friends, you have no skin the in the game and this all a fun debate for you.