A couple, I think. WoTshow is one I really liked. And exatheist is a tiny sub where a bunch of people who were once atheists of all different religions talk religious philosophy.
It'd be great to have an actual place that isn't just Christians screaming that LGTBQ+ people are of the devil and need to burn, and at the same time not have edgelord atheists decrying that they have figured out everything and are smarter than everyone else
This seems way too unlikely to happen, but r/askhistorians. It's an exceptionally well moderated (if a bit overzealous) community that allows for both the average person to ask seemingly impossible, very specific questions as well as academics to express their knowledge and passion for those very same super specific topics they find fascinating; but have difficulty finding an audience to listen to them in their day to day lives.
I'm really hoping for some quality archaeology/anthropology/history content as well, I started !humans@terefere.eu for a kind of catch-all community (and yes, that's the best name I could come up with)
A lot of these aren't exactly "niche", but afaik none of them exist on lemmy yet
Edit: for some reason, a bunch of these that actually do exist weren't showing up in search unless I specifically searched for "!community@instance". I've gone back through and added links to them here.
If any sub can truly 100% move over it'd be one of the Linux subs, maybe then they'll stop posting memes about how they're posting memes on a closed source platform
Hello from !ultralight@lemmy.world, I always wanted more overlap between r/ultralight and r/myog personally, they go hand in hand. Stop by and say hi :)
I've seen a few people mention fighting games on here (e.g. Street Fighter). I'd be interested in that. The number of gameplay clips people would be sharing make me think it ought to be its own instance, though.
Also:
pens, fountain pens
mechanical keyboards
watches
Some communities have been created for those, but don't seem to have gained much popularity.
r/HobbyDrama or a more hobby oriented history community. Also r/AskHistorians or similar, although that one will take more effort and setting up than simply making the community. I personally use Reddit to see a couple memes and then read both of the subs I mentioned. I like seeing people who are passionate about a thing talk about the history of that thing.
r/buttcoin, every time I feel bad about myself I like reading about crypto fails to remind myself that I could have made even worse decisions. r/noncredibledefense, makes the horror of the war not far from me a bit more bearable
Late reply but I just randomly saw this and thought you might wanna check out !virtualreality@feddit.de which seems to be the biggest vr community right now!
Maybe~~ r/iwatchedanoldmovie
~~
Some game specifics sub's like r/MetalGearSolid, r/MetalSlug and r/HalfLife, r/moddergearsolid is a particularly obscure one.
From my own feed that's about it, with the exception of some piracy ones like rCemuPiracy r/LinuxCrackSupport and r/SteamDeckPirates, among others. And a couple in particular that push a bit closer to the work unsafe side, so those wouldn't be here.