https://lemmyverse.net/communities

Lemmyverse will let you search every community hosted by Lemmy instances that share data with it, which is most. If you set your home instance before you start clicking links they'll open on your home instance so they are easier to subscribe to.

Here's a recent post I put together with some more resources:

https://walledgarden.xyz/post/1600683

Edit- Also worth mentioning the Voyager interfaces offer a solution for this.

Download voyager app then click settings, migrate subreddits

Or click search, then explore for a list of every single community on Lemmy

Which you can then filter via the icons at the top. Subscribe by clicking the heart icon

Voyager also has a community !voyagerapp@lemmy.world

Just to add semi-related, don't worry about communities having little to no recent activity. I once posted in a community where the last post was 6 months ago and got relevant comments from 5 people anyway, giving me exactly what I wanted.

1. Post topical AskLemmy questions about some deep cut from the subject
2. Some helpful Samaritan will often direct you to the or a relevant community
3. pay it forward and do the same. We all win when everyone easiky finds their niche and gets their freak on here. I definitely like to watch ( ͡° ͜ʖ ͡°)

I have experienced this directly many times so I know it works

Try looking in this list of corresponding communities.

Also this.

Try to list the subreddits you can't find as similar communities here and we might direct you somewhere.

The Voyager app helps with this.

If you require some superb owls, we just started the quarter finals of the 2nd Annual Lemmy Owl of the Year bracket tournament over at your federated owl-ternative destination, !superbowl@lemmy.world.

This site does a pretty good job of what you’re asking

https://sub.rehab/

not that I know of. someone had a recent question about all. My personal strategy is to peruse all and block communities I have zero interest in. Like I have no interest in sports so I get rid of all those. Concurrently I subscribe to things im really interested in. I put blocking first because it reduces what you see so makes it easier to find what you really want. Once you have subscribed enough you start your scrolling day in subscriptions and when you run out you go back to all and maybe you come across something new to subscribe or whatnot.