There's Nextcloud Social, which is a social network built in to Nextcloud that connects to the Fediverse. Nextcloud is already a hub that does a lot of things (file storage, email, notes, calendar, word processing etc), so for business users and organizations it might make sense to have a social network solution built directly into Nextcloud.
It seems not to be in active development though. Which is a shame - it would be neat if self hosting Nextcloud gave you the option to easily have a self hosted handle on the Fediverse along with it.