There's a new groups system for the Fediverse called chirp.social. More info at:
➡️ chirp.social
You can join a group by following the group account. You can post to the group by @-ing the group account, which then reposts that to all its other followers
It is similar to the existing a.gup.pe system, but chirp.social allows a group manager to delete posts and ban people from the group.
It works on all Fediverse platforms including Mastodon.
chirp.social: groups for the fediverse
Create groups for Mastodon and other ActivityPub-enabled apps.chirp.social