@ntnsndr Co-op/collaborative adim or selfhosted online communities and other tools: yes!
But I think a lot of care needs to be taken when thinking about which parts define an online identity (and thus don't change or change infrequently and/or are mutually exclusive if you want multiple simultaneously) and which parts are communities your identity participates in.
Roughly, in my mind anyway:
Email, username, etc: identity
Discourse posts, toots, files, slack messages: things done by the identity.
Not the best expression of my thoughts here, but hopefully that's interesting, at least 😀