If by "connected" Wikipedia don't mean a technical protocol, but a connectedness in spirit, then the communities gathered in mailing lists are no less a part of the Fediverse than the more recent phenomena like Mastodon, Friendica or Hubzilla. And if the technical interface to mailing lists is missing, then this can be made up for ;-).
All friendly creatures are welcome. Be excellent to each other, live humanism, no nazis, no hate speech. Not only for nerds, but the domain is somewhat cool. ;) No bots in general! (only with prior permission). ---