Sympathies, OP.
All but one of my kids know what a woman is. Such a relief to talk to them, when the oldest can't see the wood for the trees.
When, years ago, the oldest told me that a girl in their y10 class had become a boy, I assumed that naturally the oldest would know that this was purely metaphorical. Metaphysical at most. That it was the same person but with shorter hair and a shorter name. Whatever floats your boat. Continue to be kind to them. Really thought nothing more of it.
But apparently it was not like this for oldest. They thought that you could literally do this. On a word, a complete change of sex. And, about a year or so later, oldest said that after thinking about it for a couple of months, they thought they might feel more comfortable as a girl.
I have a theory that this generation are so used to customising avatars, creating skins, deciding to play as the opposite to themselves and switching everything in an instant that they think the real world is up for grabs in the same way.
Real life is so 'vanilla', so normie, they hope to create something more interesting. Manipulating images of themselves, filters, curating their content is second nature to them. The fact that they don't know who anyone is online means also that they can be anyone online. "What's material reality got to do with anything?" says oldest, scornfully.
And it is very seductive. In an instant your stock rises. You get 'centred' and, in spite of your white male MC obvious privilege, you get to claim a little bit of oppression. Or 'queer' your relationship. A kid who was too scared to get their school leaver booster jab because "needles" suddenly talks about an extensive range of desired plastic surgery as if they are ordering at a fast food restaurant.
The other thing is that our kids do crave something to rebel off, to differentiate themselves.
As I see it, there has been a collapsing of the cultural difference between the generations.
Where my grandparents were brought up by Victorians and so passed on some of that baggage to my parents' generation, I think my generation's experience is more similar to that of my kids. We decided that we weren't going to parent in the same strict way as previous generations, we increasingly like similar music to our kids, enjoy the same films, maybe dress relatively similarly, went away to uni, went travelling, struggled to get jobs, houses etc
My husband has a somewhat colourful past and we used to joke that it would be pretty hard to shock us as parents.
How wrong we were!
Oldest found the 'gender identity' chink in the armour and we never saw it coming.
The embracing of a vegan, star signs, pansexual, antifa, ACAB, BLM identity was then just a matter of time and we were ready for that. It's a question of positioning yourself so you are not like your family.
In terms of talking, yes we generally now tend to avoid gender as a topic as it usually does not end well. "Adult human female" is, apparently, a transphobic dog whistle. Which is tough when you are talking to one. Who has just cooked your dinner.
The rage/demands for safety is partly because gender ideology has an unstable fallacy (sex ≠/= gender) at the heart of it and so these kids struggle to argue effectively. It's not their fault. The cognitive dissonance is painful.
What I am becoming better at doing is talking about adjacent subjects and helping develop critical thinking skills. So, pick the concept you wish to discuss and find a "non gender" example so you leave the cognitive dissonance/parallels with gender hanging in the air... Rachel Dolezal is good for talking about how wrong it is to appropriate the lived experience of others, for example. But it is exhausting.
The daft thing is that everyone knows what sex people are, hence why your son is able to be casually misogynistic towards you but not to your husband. The woke generation are horrified by racism but remarkably unbothered by their lazy sexism/ageism, as characterised by the Karen meme.
And, final proof that that it is a pretence that sex is so easy to change? If your DS was to be sexually active, only his non binary girlfriend would be at risk of getting pregnant...