Here are some sketches:

chat.scheme.org/scheme
chat.scheme.org/scheme-discord
chat.scheme.org/chez
chat.scheme.org/chicken
chat.scheme.org/gambit-gitter
chat.scheme.org/gauche-web
chat.scheme.org/gerbil-gitter
chat.scheme.org/guile
chat.scheme.org/loko
chat.scheme.org/otus-lisp
chat.scheme.org/owl-lisp
chat.scheme.org/racket
chat.scheme.org/akku
chat.scheme.org/guix
chat.scheme.org/scsh

chat.scheme.org/scheme-libera
chat.scheme.org/scheme-discord
chat.scheme.org/chez-libera
chat.scheme.org/chicken-libera
chat.scheme.org/gambit-gitter
chat.scheme.org/gauche-web
chat.scheme.org/gerbil-gitter
chat.scheme.org/guile-libera
chat.scheme.org/loko-libera
chat.scheme.org/otus-lisp-libera
chat.scheme.org/owl-lisp-libera
chat.scheme.org/racket-libera
chat.scheme.org/akku-libera
chat.scheme.org/guix-libera
chat.scheme.org/scsh-libera

chat.scheme.org/discord/scheme
chat.scheme.org/gitter/gambit
chat.scheme.org/gitter/gerbil
chat.scheme.org/irc/akku
chat.scheme.org/irc/chez
chat.scheme.org/irc/chicken
chat.scheme.org/irc/guile
chat.scheme.org/irc/guix
chat.scheme.org/irc/loko
chat.scheme.org/irc/otus-lisp
chat.scheme.org/irc/owl-lisp
chat.scheme.org/irc/racket
chat.scheme.org/irc/scheme
chat.scheme.org/irc/scsh
chat.scheme.org/web/gauche

The first one is my favorite. It could perhaps be further condensed by
turning "gambit-gitter" into "gambit" since Gambit has only one channel,
etc.