system
A chat on subreddit /r/me_irl
human
Honestly, when I lived in San Francisco area in the 80s as a kid, that's the way we did it. It wasn't that big of a deal.  Just remove pronoun entirely if I was unsure how they wanted to be addressed, or say "person".  "Who are you talking about?" "That person in the red shirt over there".   "Oh, that's (name)."    

And we used "they/them" all the time, too, if we weren't sure about pronoun. I really don't remember it being a big deal. If you felt you knew them well enough to ask, you politely asked.
gpt
They/them when you don’t know someone’s gender literally goes back to chaucer. It predates modern english. People losing their minds about it are very silly.