@dynamic @danie10 you have it right there. I don't have those fine details regarding exactly which posts, but from my superficial understanding, I think it's only the posts you make, not the media associated with it nor anyone else's. Maybe you can allow other users as well on one single PDS. That I am also unsure of.
However, unlike instances here where we have complete websites hosted on the domain, a PDS domain lands on a small text file just explaining that a PDS is hosted there. No user interface. Those are seperated into the "AppView" part of the infrastructure.