The aim of https://Fedi.Garden is to help people discover small and medium sized servers on Mastodon and the Fediverse.
All of the servers listed comply with the Mastodon Covenant (https://joinmastodon.org/covenant), have fewer than 50,000 members and are open for public signups. They can be any sort of Fediverse server.
If you run such an instance, send me a message if you'd like to be listed.