Some people think that "Mastodon is too much about just tech all the time", and that's really missing out on a lot of what the fediverse is. It's a grand tool, but one you have to use with intentionality and find the things you want to interact with, because there isn't some omnipresent algorithm trying to drag you into addiction.
People who want to follow certain topics can follow hashtags, or they can also participate in lemmy communities (I think? I tend to use lotide to interact with lemmy communities since they're kind of the same sort of thing).
@realcaseyrollins for example has done a fantastic job of consistently posting on a wide variety of subjects to lemmy communities. He used to be on lotide but unfortunately that project ceased development earlier this year so he decided to officially move to lemmy entirely.
I believe you can subscribe to communities on lemmy (I'm looking at his history for examples, which is why they are where they are) as if they were users, so for example if you wanted to see all the posts about celebrities from thelemmy.club, you could follow @celebnews or if you wanted to follow the movie community on lemm.ee, you would join @movies. There's tons of options out there, and lots of things being posted and discussed on a regular basis.
I also believe subscriptions to magazines (communities) on kbin also are compatible with mastodon, so if you wanted for example to see a bunch of stuff about industrial design, you could follow @[email protected] and see a bunch of discussion on that topic.
With Mastodon, the ActivityPub support means you can also do cool things like subscribe to your favorite Peertube channels (assuming you have favorite peertube channels). A lot of them are tech related, but for example on makertube.net there's @thegiddystitcher whose channel is about sewing and knitting. Having videos from this platform show up in your posts is pretty exciting, it's an example of how something completely different than mere messages can integrate using the ActivityPub protocol.
There are also other parts of the fediverse that are relatively new but may be quite unique and different. For example, you can follow people on minds, which is a fairly large social media platform in its own right with some media personalities having active accounts there. Threads is a big corporate site, which means that some instances block them by default and some instances are blocked by default, but if you're on a mutually friendly instance it has a lot of users as well that aren't likely to hang out on smaller instances.
It's not as straightforward, but you can also follow and interact with people on nostr through the mostr bridge. There's a lot of bitcoin and the like on mostr, but it's still another option. You can follow former twitter CEO Jack Dorsey at @82341f882b6eabcd2ba7f1ef90aad961cf074af15b9ef44a09f9d2a8fbfbe6a2 (just rolls off the tongue, doesn't it?)
There's also portions of the fediverse that you won't know about unless you actually know about it -- for example, journa.host hosts many journalists, as well as the fediverse pages for a number of news organizations. I follow @winnipegfreepress because I used to live in Winnipeg for example.
There are also a number of notable celebrities on the fediverse. American idiot George Takei, famous for saying "oh my!" provocatively, has a very active account. Fascism advocate Robert "Third" Reich also has a very active account. A wide variety of other celebrities also have accounts, for example famous genocide activist Greta Thunberg and red painted doll head collector Kathy Griffin, but typically many of these accounts were created during hissy fits about something or other, and like most political hissy fits by celebrities they gave it up once they realized nobody cares. The fact that they can't just hire someone with thick glasses to game the algorithm was probably a major factor in leaving since they're not special on the Fediverse.
The fediverse really is like the old story of two wolves being inside of you. Whichever ones you feed are the ones that will grow. If you're doing it right, you can have any kind of feed you'd like and you'll find it really enjoyable.