always wondered this, but kept forgetting to post it
eg users would be on @grant@toast.ooo and a community would be on @canvas@group.toast.ooo or something like that
then it would still follow the AP spec but still allow for identical identifiers (like a user account being @sc07@toast.ooo and a community also being !sc07@toast.ooo)
I dunno about Mastodon, but Pixelfed says they’re working on a “groups” feature which should be compatible with Lemmy communities. It’ll be interesting to see how they solve this issue—if they do address it at all.