I don't think you understand me.
Gender critical does not mean "I opt out of gender for myself as an individual in the hope that society will magically respect that".
It means "I challenge the myths of gender within society in the hope that more and more people will see them as the limiting falsehoods that they are and stop framing both their own identity and their understanding of and interactions with others through gendered constructs at the personal, instiutional and legal levels".
Yes, that is likely to include some degree of rejecting genderised behaviour and presnetation for myself, because why would I choose to align with beliefs I consider harmful, but it's not by any means the whole of it, or even the largest part. Primarily, it's about pushing for social change not personal identity.
So I'm not suggesting Lucy becomes somehow unsexed or pretends she is unsexed. Her sex is a fact that will always be recognised, and to some degree - though until we get rid of gender, the social constructions laid on top of sex, we do not know to what degree - she will continue to face challanges because of her sex. Even in the most perfect, unsexist world there can ever be, even if it could be possible to have a world were men no longer choose to rape, her physical strength will limit her compared to many men and her reproductive role will impact her more than it would a man.
But nevertheless, there are also social constructions that contribute harms on top of whatever baseline sex-based harms there may be, and those harms can be challenged and can be reduced. And that is what Gender Critical feminism is about.