I think independent social media like the Fediverse has uses with any group who would appreciate local control and free expression. I think the witchy community would fit that bill. I am unaware of any projects about it. At a certain point of users it would be inevitable just need someone connected enough to get it started.

Unrelated but I figured at a some point sex workers would flock here. Locally controlled by sex workers for sex workers would be a huge sell because they can’t be kicked off by arbitrary rules.