Earlier quoted context omitted.
It's not "absolutely true in the scientific sense", except at the "I have an understanding of high school level biology and sociology" sense. Sex and gender are both significantly more complex than just chromosomes, genitalia, or organs. If you are interested, I'm happy to dive into a good faith discussion of where the science actually falls.
The only real discussion to be had is that you and I mean (very) different things when we use the word "woman".
I'd argue that most women, in fact probably 99% or more, fall into a fairly straightforward definition - two X chromosomes, raised to behave like whatever their society expects from women. (I think we can agree that "woman" might have different cultural/social expectations depending on where they were raised? E.g. in some parts of the world a niqab or hajib is expected, for instance.)
But there exists a small group of people who don't fit in with that definition. They might have been born with a penis but two XX chromosomes, they might have been born without functional ovaries or an abnormal set of genitalia.
They might have been born with XY chromosomes but never developed a penis.
These folks are intersex, and are often raised as women.
I would say, in these cases, that we might agree that they are women - their chromosomes might not always be XX, but all their features and body development and social upbringing in the world suggests that they are women.
Then we come to another group. A group whose bodies are functionally male but who feel a deep revulsion at being a man.
But before we dive in to that case, are you comfortable with the other two cases and have any disagreements about the 99% or intersex cases?