I have met trans activists though that DO deny sex. For example while you’re right, sex is more complex than chromosomes and can involve various physical and hormonal expressions (someone could have XY chromosomes and physically have female secondary sex characteristics due to a lack of androgens in the womb, so if a trans person with XY chromosomes changes their secondary sex characteristics I would say they have a good argument to call themselves “female” as well as a woman), I’ve literally met trans activists who say “I am a woman thus I have always been female, to say I ever had male body parts or male chromosomes is transphobic”. I’m not exaggerating. Many trans people DID and to some extent do have the biology they were assigned at birth. To say so is not transphobic. Yet apparently to a loud and vocal minority simply agreeing with science is bigoted. I have a problem with that, and I’ll never bow to demands that we change the definition of sex to “whatever I identify as” — that is gender not sex.