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, are open for public signups and block threads.net. They can be any sort of Fediverse server, not just Mastodon.
If you run such an instance, send me a message if you'd like to be listed.