Personally I would feel arrogant asserting what’s in anyone else’s mind or disputing their identity. I’m open minded about what we may yet prove scientifically and how other individuals experience life.
However I don’t think it does or should makes a difference in any practical sense to public life. Single sex spaces and adjustments have always been based on the material reality of the recognition of the two types of biological person, with different needs and risk profiles.
The female individual has different biological characteristics and needs - and other needs flowing from that - to the male. Their biology means that eg they don’t just use toilets for waste but for menstruation, miscarriage, menopausal flooding, pregnancy sickness and the greater incidence of bowel and bladder disorders and digestive issues that arise in females due to biology. They take longer in the loo, undress more, and are more likely to have small children to cater for.
Males carry out 98 per cent of violent crime and all rape. The overwhelming majority of females will have experienced sexual harassment of some kind in the period from adolescence onwards, virtually always from the male class.
For hundreds of years, the sexes have been split for these reasons and for longstanding cultural and religious reasons when undressed etc. Therefore it makes sense for society to protect places where females are vulnerable or incapacitated for their safety, privacy and dignity e.g . hospital wards, prisons, changing rooms. This is necessary for the wellbeing of the majority.
Biology is also the key determinant in sporting prowess and success in most - not all, but many - feats of strength and sporting prowess This has always been recognised until very recently by separate categories for the sexes in sport.
My heart goes out to individuals who don’t fit into neat categories. I can feel empathy because I think there are few of us who haven’t felt something in the same universe (obviously not the same or as severe) at some point in our lives. But a society that doesn’t recognise the reality of the biological separation of the sexes and the safety and privacy needs of females is deluded and rotten. We have to run public life for the greatest good of the greatest number. That doesn’t mean not recognising the needs of the minority and trying to protect them from harm - but that can’t be at the expense of the valid reasons for the sex differential.