But, I don't think he/she is viable because a major use case is people pasting quickly on their phones. You can see this because the app has automatic clipboard copy built in.
He/she has always been pretty awkward and silly. But in the eyes of at least some people, it also has the failing that even after all that it still assumes binary genders.
Curious, I looked for guidelines and the best I could come up with was this, which seems helpful if you know the person in question, but not so much if you're referring to someone completely unknown: https://en.wikipedia.org/wiki/Third-person_pronoun#Transgend...
I welcome advice.
Singular "they" has a long history of being used as a generic pronoun, before a bunch of white men decided in the 18th century to try and prescribe "he." Singular "they" is making a comeback, though, and in this case it would be appropriate.