I run my own instance and I have created some communities that I loved back on Reddit. I searched and no similar communities seem to exist in the fedeverse yet. Obviously there is nobody visiting them right now, so how would you go about trying to promote it to attract some discussion?
You can try posting them on newcommunities. https://lemmy.world/c/newcommunities
Just remember to post them so that we can all get to that community from different federated !newcommunities@lemmy.world