Non-binary seems like it could have several non-compatible meanings, so I wanted to list some of those meanings and see if there are any others out there I don't know.
One way I could think of non-binary is as being a kind of third gender category, like there are men, women, and non-binary people. In this sense of non-binary a butch woman who considers themselves a woman would not be non-binary because they are a woman.
Sometimes non-binary is used like "genderqueer" is sometimes used, as a generic description of anyone who doesn't fit perfectly in the narrow confines of the binary genders (i.e. men and women). In this sense a butch woman could see themselves as a woman, but also as genderqueer and non-binary, as they do not conform to binary gender norms for women.
Another way non-binary seems to be used (related to genderqueer in its historical context) is as a political term, an identity taken up by otherwise cis-sexual and even cis-gendered people who wish to resist binary gender norms and policing. In this sense even a femme cis-sexual woman might identify as non-binary. Sometimes this political identity label might come with a gender expression that cuts against the gender expectations for the assigned sex at birth, but it doesn't have to. (I recently met two people whose gender expressions matched their assigned sex at birth but who identified as non-binary in this political sense.)
I was wondering what other meanings of non-binary are out there, and how they are commonly used.
Note: gatekeeping what is "really" non-binary seems pointless to me, since I agree with Wittgenstein that "language is use".
I know people get heated about policing what a word means (and I am guilty of this myself), but in the interest of inclusion, pluralism, and general cooperation in our community I think we can find a way to communicate with overlapping and different meanings of a shared term.
I think that Isogender is still different from trans in different ways, even if some trans people have similar feelings of lack of AGAB relevance, Isogender people still aren't trans because we don't feel trans acurately describes us, it's very much a self-identification type of thing, and since trans can have either very fine or very broad (up to all encompassing) definitions there can be a lot of overlap in similarities but they are still different modalities altogether.
Isogender is very rare so there aren't very many accounts of the experiences of us, I've seen a handful of people talking about it but overall I only ever saw a handful of people on Reddit talking about it, and one, maybe two other people on the fediverse who identify as Isogender or one of the other Gender modalities.
Yeah it has to do with differences in experience and identities. Even though there has been a lot of effort to expand and broaden 'trans' it still very much implies something that doesn't resonate with a lot of these people, myself included, hence why other modalities exist.
I see the merit in that but at the same time I'm not really a fan of grouping people under one giant umbrella that also happens to be its own specific thing, i.e. there are trans people who are just trans, binary trans and nothing else. I think recognizing the differences in identities is just as important as the need to unify, and that's why we added the Q+ to LGBT, for all those people with sexuality and gender identities that don't necessarily align with the other 4 categories. Maybe to some this comes across as me trying to separate identities from trans, but I'm not, people can identify as trans if they feel its right for them, I just think they also should be able to not if it doesn't and have that be respected and understood.