It’s not federated by any means, but if you want to replace FANDOM wikis with other equivalents, Indie Wiki Buddy is a great extension to have on hand.

https://getindie.wiki/

There’s options to remove FANDOM from search results in favour of other options, and they also allow you to redirect to the Breezewiki frontend for FANDOM to get rid of all those shitty ads and UI, which is legal considering the contents of FANDOM pages are still under the Commons.

Honestly depends, but if you want an all-around good instance on a misskey fork, try lethallava.land

Honestly Misskey forks for all their flaws can absolutely take this opportunity to properly advertise themselves as viable alternatives. As someone who uses a Misskey fork, I love the UI in comparison to Mastodon, and the communities in Misskey forks are a lot less techie and a lot more laid back and goofy most of the time from my personal experience.