But to be honest, XMPP (contrary to Matrix) doesn’t try very hard to replace IRC. Its much more used for 1:1 and private encrypted group-chats similar to WhatsApp/Signal etc. And joining IRC channels is so seamless from XMPP that the IRC users don’t even notice (also contrary to Matrix).
There is a room search engine for XMPP: https://search.jabber.network/
But to be honest, XMPP (contrary to Matrix) doesn’t try very hard to replace IRC. Its much more used for 1:1 and private encrypted group-chats similar to WhatsApp/Signal etc. And joining IRC channels is so seamless from XMPP that the IRC users don’t even notice (also contrary to Matrix).