an excellent point, if kind of sad (that there is so little).
honestly, this is kind of why i asked for headcanons. i only have one character i view as aro-allo (Miranda, from Black Sails), and she is excellent, but the text for sure wants her to be allo-romantic as well (and this is in a show with many queer characters, including one ace one, that shows that without using modern labels (as it's set in the golden age of piracy)).
i guess i could lay out what i have of them so far?
they are NB, and aro-bi. very outgoing and flirty (as an opposite to their android friend), who likes their encounters but doesn't want serious relationships. i'm toying with the idea of giving them multiple, long term partners. they're not sex-crazy (and as you say, some allos are, and that's extremely valid!), but they enjoy sex and they know what they want, and they're very comfortable with not co-habitating with a partner or having a QPR.
i'm still drafting their background and such, but they're the daily manager at a cafe-bar (hence the barista/bartender title), one of those extremely ~ cool ~ people who is also very likable, simply bc they like people. they can have difficulties realising when people aren't interested in socialising, and can be a bit too blunt at times. I'm thinking their family culture is such that that's necessary; when they grew up there wasn't room for subtext and interpret actions. kind of based off of my sister, in that whenever we go out together she always bumps into someone she knows.