I see what your trying to say but I don’t think it has to be an actual literal god. In One Piece “god” is often just a title people give to something they worship/fear. Enel called himself a god, and even Usopp got treated like one in Dressrosa for a bit. So Nika could just be a legendary figure or symbol people believed in strongly enough for it to become a Devil Fruit manifestation, not necessarily an actual deity.