I wonder how much of my difficulty understanding nonbinary identities comes from having been in sex work for sooo long, where the genitals you have are incredibly important to how you're treated and the role you play.
This might be a little reductive, but even in sex work, there are niches outside the binary? E.g. you brought up Buck Angel. Trans performers of many stripes, trap/crossdressing, furries etc... and, depending on def. of sex work, text/drawn/cgi porn.