Okay, so the second one, got it. But you should be aware of your bias here because even in your own model you’re just flat out wrong.
So, if I were to say, “okay, I accept that transness is a purely psychological phenomenon,” you would still be wrong because there are 3 sexes and (in your opinion) genders. There are males, females, and intersex people that don’t have simple XX or XY chromosomes. This is objectively indisputable.
Now, I want to progress the conversation, but again we’re running into the same problem of you being unwilling to grant a working definition for the purpose of discussion. You don’t have to believe it to explore it is what I’m saying, because if you are unwilling to, then the conversation only goes one way that automatically confirms your point. Like, it’s just an unfair framing that sets rules for a conversation that nobody wants to have unless they’re trying to virtue signal or circle jerk.
Not to mention that this idea that anyone is trying to cram pronouns and ways to treat trans people down anyone’s throat (outside of strictly professional ethics), is just not a thing. Like, no trans person wants to unpromptedly force someone to call them something. Most would just try to correct you politely and if you refuse to, they’ll probably just stop talking to you. The only time that a trans person is going to have that argument on an individual basis is if they feel attacked and get defensive like anyone in any situation in which they feel attacked in some way.
Also, I’d make a final point that “NonBinary is not a valid gender” is just kind of dumb and pointless because it doesn’t change the fact that even if it is only a psychological thing, it’s still a readily observable phenomenon that seems to need to be addressed.