There is no widely recognized identity for those who are nonbinary and are only attracted to women. I would say that AGAB does have something to do with it. Personally, I didn't realize why some with they/them he/him pronouns would identify as a lesbian until someone I know chose to identify that way. They weren't a woman, but they also weren't a man, and they only found female parts attractive. Certain people aren't attracted to certain parts - AND THAT'S OK! For those who are AFAB and only attracted to AFAB people, there's not a well known label that will actually be taken seriously, but "lesbian" conveys the sense of being a female person who is attracted to other female people. Even if an nby uses he/him pronouns, identifying as "straight" doesn't really work because they're not a man, and so their attraction to women isn't attraction to the opposite gender. In my experience with they/them lesbians, the lesbian label is the only label that "feels" right and conveys who they're attracted to.