There's some site that's designed just to use a bot account on various major instances to subscribe a new community. It waits until there are something like 10 regular users subscribed, then unsubscribes. You could just plonk in a community name and have it do so. That helps discoverability but kind of clashes with the whole intended scalability decision in lemmy/kbin/etc design not to slurp in content from all communities out there.

I think this is the github project page, but someone was running an instance of it.

googles

Man, I can't even find the instance that someone was running, which does kind of maybe highlight the need for a central "Threadiverse wiki" that links to all this stuff. fediverse.observer, lemmyverse.net, fedidb.org, join-lemmy.org, etc. There's some other tool that someone made to measure post federation latency, so you could see what instances are overloaded or not working. There are a ton of useful tools out there, but no central hub. I keep finding them when someone links to them on the Threadiverse and then never being able to find them again.

My own home instance, lemmy.today, has always had a request in the sidebar asking people to subscribe to a bunch of communities so that they become visible to the instance, which seems like kind of an awkward workaround for discoverability:

🥹 Make sure to join a lot of remote communities to get a good feed going. How to do that is explained here.