Maybe burggit.moe? They're defederated by the bigger instances because of loli hentai.
Other than that and lemmynsfw, the only NSFW instances I'm aware of are pornlemmy.com and lemmyf.uk. Pornlemmy is specifically focused on vanilla. I'm not sure what exactly lemmyfuk has. It really annoys me that none of these instances show anything if you aren't logged in, not even a list of communities. Yes, I know it's a limitation of the software.
EDIT: Now that I look again, pornlemmy has applied a patch to show NSFW without login, like lemmynsfw used to do. Good on them. Still vanilla though. ¯\_(ツ)_/¯
lemmynsfw.com will definitely show communities if not logged in, and you can see everything if you open one. pornlemmy.com shows everything if not logged in. Both of these are from a web browser, and in my experience if I click on a communty from my feed in either connect or liftoff. and if you hit settings and on each instance, by default they are set to filter stuff for not logged in, you can turn that off, even if you're not logged in.
Huh. Terminal curiosity, but randomly clicking through, I saw a lot of 2000's era racist/sexist humor, mostly banning NSFW, one entirely made up of github links and anime girls, a weirdly normal Reddit clone, and... one that was suspiciously banned from the internet lol.
So, at least one person got Hansen'd. Which, I can't imagine what they thought was gonna happen there.
I can‘t even find the @nsfw.Lemmy.world communities?
I have NSFW enabled on my account on on my instance (Memmy for Lemmy), and I‘ve seen very few NSFW posts, but why can I not search for them?
There are very spicy ones where they don't take laws into consideration. Would not recommend visiting unless you want to end up in a government watchlist.
Edit: Probably listed in the list of instances in [Instance-URL]/instances (for example, lemmy.world/instances), and you can see "Linked Instances" and "Blocked Instances" and if you wanna see spicy stuff go visit the blocked stuff. Again, some of those might put you in a government watchlist. If you do decide to visit those, Chris Hansen might be asking you to take a seat.
Can't yet, just have to block individual communities. Kbin users can block domains, but that's not the same as blocking instances. For example, you can block imgur.com to avoid seeing posts that link to imgur.