I don’t think it’s a movement.
I think there’s a collection of ideas that varied people believe. not all those people will have the same ideals across the board or even anything in common other than refusing to accept how you present defines your sex (and for all this “no, it’s gender, it’s different!” It’s sex that matters otherwise third spaces or acceptances of men who ID as trans or nb in male single sex facilities would be seen as more acceptable).
To compare, you can look at animal rights and say there’s hunt sabs, those who release animals from labs and target stores that sell fur with graffiti attacks, there’s also little old ladies who feed all the squirrels, stray cats, birds, hedgehogs and donate to every animal charity going, whilst also sitting down to a roast dinner on a Sunday and ham sandwiches for lunch. Plus vegans who bore on about their new plastic shoes all over insta and little kids who love animals and tell everyone they meet how great animals are and can we have a pet lion etc. they’re not a movement, they’re people who care about animals in varying degrees who probably have nothing else in common. We wouldn’t call them a movement.
GC feminists reject the stereotypes of “gender” and see it as harmful, which I guess has grown out of basic feminist principles. As things have got more public (and extreme) more people have got involved. As mentioned up thread there’s younger women who haven’t had the battles feminists of the past have had and this is there entrance to feminism. Then there’s people who have very set views of what a man or woman should be-no more the natural bedfellows of feminists than the right wing evangelists who see porn as immoral were allies of feminists who see porn as violence against women.
I still can’t see how the absolute sexism of the recent trans movement can be compatible with feminism. It isn’t liberating anyone from stereotypes, it’s cleaving to them and once you look into it it is wholly negative for women. You only have to read the words of the transwomen who post about themselves here to see that “woman” or “girl” is a set of stereotypes to them and ones that we’ve been kicking against for a very long time!
Personally, I wouldn’t say I was a GC feminist anymore than I’d say I was an Equal pay feminist or an Anti Sexual Harassment feminist or any other single issue, because those are such basic elements of feminism it’s all part and parcel of the whole thing.