jointhefediverse.net seems to be a commonly linked resource for directing people to join the Fediverse.
Curiously, it does not list Lemmy under the list of Reddit alternatives. Their GitHub README explains why.
Previous relevant discussion: https://lemmy.ml/post/78808
Oh yeah, sorry. I didn’t mention that the API isn’t available on production sites like piefed.social. I’ve been messing around with a build of Thunder on my dev instance, and - among other things - the app doesn’t uses the same V3 endpoint that Lemmy does, so it’d always need to be a different version than the one that’s currently available for Lemmy.