Of course trans people exist. They're not going anywhere. Gender dysophoria - I've experienced bodily dysophoria if not gender-related so have some insight into this - is a very psychologically painful condition. The gender presentation which best helps to alleviate this dysophria is not an issue for me.
This isn't the same thing as changing biological sex. Conflating the two, when it comes to prison accomodation, women's sports or anything else that is at risk of harm from this biological difference, is a legitimate concern. I can understand this is why some people might not want to use opposite-sex pronouns which blur this distinction: once the clear definition of 'woman' has been muddied, it's harder to stick out for the rights of biologically female people.
As to non-binary, if people want to identify as such because they reject regressive gender stereotypes, I have no issue with that at all. The caveat is that this is as long as they don't attempt to ride roughshod over women's separate rights. I reject regressive gender stereotypes too. So far, we are equal. The 'they' pronoun only grates on me because it's grammatically inaccurate, which is a 'me' issue and admittedly a small one.
In my perception there's a clear difference between trans people and the aggressive MRA activists who have misappopriated their rights for more nefarious ends. In my profession I meet and work with trans- and non-binary people a lot. I've known the old-school transsexuals people talk of, and for the most part they have been harmless, peaceable people. A couple had the kind of paraphilia whose existence is denied by TRAs, and which as a consequence doesn't bear mentioning on MN. They admitted as much.
The problem with breaking down boundaries between women and trans women is that we don't know at a glance who the peaceable ones are and which present a danger. It's the same rule, in fact, which applies to our everyday dealings with men. And we all know if those boundaries are breached, predatory men WILL take advantage.
It's possible to have deep concerns over women's rights and still broadly support the many, many decent trans people out there. But of course this isn't good enough for the more aggressive lobby. Total capitulation is required or you're a bigot who qualifies for The Acronym.
I call people by their desired names. I don't deadname people. But I'll avoid gendered/sexed pronouns by bending language to eliminate these. This isn't 'transphobia'. It's a clear way of ensuring no one is offended and that there is no active harm done either to trans people OR women.
Women matter too.