h is a user on social.coop. You can follow them or interact with them if you have an account anywhere in the fediverse.
A lot of organizations I care about used to have an IRC presence (eg Creative Commons) and moved primarily Slack based on the justification of "well there's an IRC / XMPP bridge". But it turned out that was a bait and switch: https://opkode.com/blog/slacks-bait-and-switch/
