At the moment there is slim pickings for other communities to join if this instance is chosen by a user to be their home server.

Presumably other instances have to approve linux.community federating with them before their subs can show up? Is it that this instance is new, or is there some other reason. u/nkukard can you chime in?

EDIT: A-ha! I was searching poorly! Once a member of a instance subscribes, it pulls it into that instance for easier discovery. Neat!