Just a note, correct me if I'm wrong, but it's possible to "follow a hashtag" on mastodon, which will influence what appears in your timeline.
BUT, as of version 4.0.2, there is no way in the UI to see what hashtags you're following.
I accidentally clicked to follow a weird, obscure hashtag, and was getting some wacky stuff in my timeline. I finally figured out why, and could "unfollow" the hashtag, but only when clicking on it again in a post.
@shawnp0wers You can also RSS-subscribe to a hashtag "outside" Mastodon. (I am not sure if some toots may not be shown depending on public-level settings for each handle). In general, it's cool that Mastodon support RSS-feeds.