To import new communities on an instance into the all feed, go to places like LemmyNSFW and look at what is active, any community that says "pending" when you try to subscribe is waiting for the instance synchronization bots to make the community available. Once this happens, everyone will see the community in the All feed for your instance. Indeed there are a lot more porn posts happening, you just have to be a little proactive about finding them.
... I know... Uhhh! Effort?!
but we all have to take some ownership to be here. This is like, the only service reddit ever provided and now, to make this place work, we have to do it. I'm the reason a couple NSFW communities are on .world, so this is not a hypothetical. There are many other instances for NSFW content too.