Yes, there are a couple of websites that categorise and provide searching for communities across the Lemmyverse.
https://www.quippd.com/writing/2023/06/15/unofficial-subreddit-migration-list-lemmy-kbin-etc.html
There's a bunch more too.
Also worth noting that you can sign up to multiple instances too. You aren't beholden to your admins in the same way that you are over a barrel at other social media websites with a single account. Your browser and all of the apps support multiple accounts out of the box.
It's honestly superior once you are used to it. I'm looking forward to the day we have federated ID to go along with it too without having to spin up a whole instance yourself.
If you're familiar with IRC it works almost exactly like that but via a website. Your browser is your client and you can connect to and sign up accounts on any server. Channels can be seen and interacted with across instances though but they are still seperate entities, which is the only difference.
Although it seems like there would be multiple communities and fragmentation what usually ends up happening is that your server fedeates other popular subs though others interacting them and they still gain traction and get popular.
The good news is that multiboxing got heavily nerfed a few years ago making input broadcasting against the terms of service.
Now wheather the game itself is in a great place or not is another story.
Cross-instance control of your identity would be nice but it's easy enough to just make multiple accounts and manage them easily in your browser and every app under the sun. We are much less beholden to power tripping arseholes here than on a platform like Reddit.
It's feeling quite good at the moment so thank you for all your hard work.