little, 'gender' doesnt' seem to me to be a feminist concept. I don't buy into Judith Butler either, FWIW.
Seems to me it's like this:
Sex is something assigned to us at birth. It is the primary way our society believes people should be put into categories. You can see how damaging this is, because babies born with genitalia that do not fit some stupid idea of what genitalia should look like have been, and sometimes still are, mutilated shortly after birth. Disturbingly, doctors have sometimes decided that it is better for a child to grow up with something that looks like a vagina (but has no sexual function) than to grow up with something that looks like a very short penis and has sexual function.
Gender is also assigned at birth. It is a social construct. I can see absolutely no reason why 'gender' is necessary at all. But it is tremendously helpful for splitting people into two groups and for perpetuating misogyny.
Many people feel unhappy with the body they have and/or with the gender they were assigned. Those people try to find ways to stay sane. This is completely understandable. One of those ways is, for some people, being transgender. Those people feel it is the best and only way for them to feel like the person they know they are. That is really important.
But, I don't think that changes the fact that gender in itself is a damaging social construct we would all be better off without.
So I can't accept that it is a pleasantly harmless idea, no.