They went live here on August 3rd, 2020
Slack didn’t get them until May 2021
Facebook had a non-binary option in February 2014, but still doesn’t list pronouns outside of profiles.
TikTok added pronouns in December 2021 but still doesn’t display them outside of profiles
Instagram added pronouns to profiles on May 13th, 2021
Possibly. That’s pretty neat. No surprise it was a queer designer spearheading it. Doesn’t look like it’s displayed outside of profiles, but that’s definitely a place where the use case is different