OP. You asked me what specific concrete things I want to change.
Nothing. And that’s my point. I want single sex spaces for women, adult human females, to stay just that. If a man identifies as a woman, however that looks or feels, with or without surgery, they are still a natal man. If their skeleton is dug up in 100 years they will be scientifically identified as a man, irrespective of their self id, gender norms, certificates etc. when they were alive.
So to avoid being woolly, my answer is to change nothing as regards the existing provision of single sex spaces for natal women, adult human females.
I notice in a later post you’ve moved onto the definition of biological sex. You state it’s not about reproduction, saying some people are infertile. It pretty much is. Males and females have their own gametes, sperm and ovum. No man has managed to change his sperm into ovum.
If a woman can’t reproduce it doesn’t mean she’s not a woman, it’s a medical/biological issue for her. So it’s not a trump card to say ah, you can’t define a woman by saying it’s about having babies as not all women can. They may be infertile but they’re still women. Some women may be unable to have a baby, but no man can ever have a baby,