HomeTown is a fork of Mastodon which lets you make instance-only posts, adjust character limits and read long form rich text blog posts.
It's still part of the Fediverse, and HomeTown users can interact with Mastodon users totally fine.
Tech people can get self-hosting instructions here:
https://github.com/hometown-fork/hometown
Non-tech people can use a managed hosting service to start their own HomeTown instance:
@gritnot
I don't know if there is any instance list for HomeTown?