Personally I've always built my follow list via manual snowball sampling, so Mastodon discoverability is almost exactly the same as on twitter, except without the useless suggestions that I have to ignore at the start.

There's really only one trick to it, search for a hashtag and use the people there to get the list started, then it's the usually check at who's posting interesting stuff and who they in turn are reposting to find potential follows.