I mean, there is a case to be made whether an object is actually an object, if no one looks at it. Ultimately, the concept of an object is entirely made up.

As far as the universe is concerned, objects are just clouds of atoms, and not really distinct from the surrounding atom cloud. It's only an object, because a human/animal looks at the cloud of carbon atoms inside the cloud of air molecules and declares it to be a chair.
If a similar carbon cloud exists behind Pluto, where no one can see it, is it a chair then?