https://lemmyverse.net/ in there you can search instances and communities, and If you Have an account on a y lemmy servwe you can use Its search function or if You use clients as Jerboa you can search communities with Its search function. I follow a lot of communities on Lemmy most of them are not as actives as their peers on Reddit but there are
For me the best are:
Special mention: BiglyBT Fork of Azureus without the shit of Azureus