@BreatheAndFocus ; @BaronMunchausen
I am including both of you as you covered some similar points.
Perhaps I misunderstood the meaning of "gender critical feminist" because of the context of it's first use in this post. I took it to mean a feminist who is "critical of" the existence of gender dysphoria. Maybe you mean a feminist that is critical of the conflation of sex and gender? I would think that would be every feminist?
So, we are all three in agreement that sex and gender are different, and that sex is not determinant of a person's characteristics or preferences. Let me start by pointing out a thing that many people do, that both of you did in your responses, that I also sometimes do, because the fact of the matter is that our culture teaches us, from the time we are wee ones, in many ways, that sex and gender do go "hand in hand." So it isn't a criticism, just an observation and one that I hope will help you when talking about these issues in the future.
@BaronMunchausen, you stated that, "...the idea that nonconformity means you may actually BE the opposite sex is actually antithetical to it because it denies gender non-conformity." Shouldn't "sex" be gender? Trans people don't say, "I'm a male/female," they say, "I'm a man/woman."
@BreatheAndFocus, you stated, "We have no problem with a man being feminine, doing the dishes, liking sewing, etc. Doing those doesn’t affect his sex though." Again, these activities are about (socially) gendered activities, and have nothing to do with sex. (It also doesn't affect his gender, if he identifies as a man. It just means he is a man that is willing to step outside of traditional gender roles and YAY!)
As I already stated, I have also caught myself making that error, so not a criticism. The point is that we only do that because the conflation of sex and gender is so deeply entrenched in our culture. This is relevant because...
Some trans people do decide to also change the appearance of their sex. (Because sex is biological, they can't actually change their sex.) They do this because they want people to treat them/respond to them/have expectations of them, based on the gender that is conflated with that sex, rather than the gender that is conflated with the sex of the body they were born with. To my way of thinking, being critical of anyone being trans goes against feminism, because it is essentially saying that they should not be who they feel like they are. Isn't that exactly what "men" have done to "women" that we are against? @BaronMunchausen, forgive me if I misunderstood that point, and/or help me understand that better. @BreatheAndFocus, also feel free to weigh in on that.
Also, intersex/DSD issues are not irrelevant to this discussion. There is a great deal of research and people that have experienced some of what is now called "gender affirming care," in an effort to force a body that was born intersex (because, yes, that does happen) to become a body that will be identifiable as either "male" or "female."