The linked instance provides a bot named after each hashtag, and it will boost any posts including the given tag, for example @fediverse for #fediverse.

Following it should include in your feed such boosts, a similar function as Mastodon’s native hashtag following, but that should be more software-independent.

Small issue I’ve observed, at least on Mbin, you need to search for the bot twice, probably the first one failing for time out as likely the first request is understood by tags.pub as “please create a bot for this tag” and it takes too long to reply back. And if that’s the case, chances are it may happen in other instances.

Found through !fediverso (post in Italian): https://poliversity.it/users/elettrona/statuses/116401619706126966