I read somewhere that on the unconscious level, the very first thing we register on meeting a new person is their sex. I would think it is probably the most important thing to know about a new person; as with all mammals, nature has designed us first of all with the urge to reproduce, thus the surge of hormones in puberty and the huge emotional turmoil in adolescence as we sort out who we want to be with and who not. Even if we end up not wanting or not having children, our bodies are designed perfectly for that role. A young woman's body is constantly preparing itself for a child.
I was very clear from the start that I wanted children, pregnancy, childbirth, the whole thing, and I would not have been interested in any "man" who was actually female, even if she managed to fool me at first. I divorced my first husband mainly because he did not want kids and could not be persuaded otherwise.
Yet: I am gender non-conforming.
As a child I desperately wanted to be a boy, got my mum to add a name to be birth certificate which had a male variation, and was called that for many years. I had my hair cut short. I never once played with dolls which I despised; I liked reading and adventures and animals. That changed at puberty.
I had a short phase in my teens when I got into fashion and makeup, but only because it was the girl thing to do and I was just marching in step.
Since my teens I have never: worn make-up, worn high heels or any sort of fashionable women's shoes, shaved my legs or under my arms , dyed my hair (and won't ever; I'm 67, now getting my first grey hairs), won't ever be using Botox or anything such. I wear comfortable clothes, mostly trousers and jumpers, wide flat shoes or boots. I'm really uninterested in looking pretty or sexy.
In spite of all the above, I've never ever been mistaken for a man. In fact, I've been told I'm a very feminine woman as I am a soft-spoken, , non-assertive type, with strong caring tendencies, comfortable in my skin and not hankering for power, not at all career oriented.
So yes, externally non-conforming. The "womanliness", whatever that is, is all internal.
I'm sure that if you were to blindfold me and lead me into a room full of men, even if they were perfectly silent, I would know they were men. There's a certain male energy I'd be able to feel and identify. I can see past clothes.