I agree with you. I think there have been people with very hard-line views on what society might look like without patriarchy / sex-hierarchy (cf a fair amount of speculative utopian feminist women's fiction, e.g. Marge Piercy).
I don't agree that this a prerequisite of being "gender critical".
I reject the idea of gender as a "thing" as I don't believe it's possible to identify a preference or behaviour that applies to all women or all men, and I don't believe that not displaying a preference or behaviour considered indicative of man gender or woman gender makes you be in the "wrong body".
I don't believe that all women are caring and maternal. I suspect in a more equal world without the judgements that fall on mothers, more women would abdicate the caring role to a partner. That doesn't mean that I think it would be a 50/50 split necessarily.
I can see why some feminists shy away from anything that it suggestive of "biological determinism" - it's like the chink in the wall that lets in the flood. "Oh, you believe X? Therefore A-Z must be true". It's been a long hard struggle away from lady brain, hysteria and the like.
All I know is that even if a certain behaviour is more prevalent in one sex, knowing an individual's sex tells us nothing with certainty about their preferences and behaviours.
I just want everyone to be able to live a happy life, whether that's with a shaved head or sparkles, in pink or blue, as a bodyguard or a nursery nurse, without being discriminated against because of what's in their pants. I think that's a pretty mainstream GC position.