Is there a community to discover other lemmy communities?

Something similar to “wowthissubexists” or “findareddit” to get a curated list rather than just searching.

This is a community that I've checked out before and even promoted my own community to, and there's some neat stuff you'll find there!

I use, in order:

or check "newcommunities"

I mostly search on lemmyverse.net though

There is lemmyverse.net.

I list a few external directories here, although they are currently largely aimed at helping people find a Lemmy equivalent to their favourite subs.

Yessir! Find a Community on lemmy.ml

Mostly lemmyverse, but also sub.rehab to see where subreddits are migrating to.

In addition to what's already been provided by other comments here you can try https://browse.feddit.de/