This idea is close to the idea of modal realism: all possible worlds are real to their inhabitants, in the same way that our world is real to us. No substrate r

This idea is close to the idea of modal realism: all possible worlds are real to their inhabitants, in the same way that our world is real to us. No substrate required. It's still fun to think how simulations or other types of "nesting" interacts with modal realism. E.g. maybe there is an "Occam's razor" type of effect where we should expect to find ourselves in a world with the simplest physics that allows conscious inhabitants, simply because such worlds have more "instances" within other worlds.