The “Garbage Dump” is a Block that can only ever be cheated in. It will emit all Items that despawn or get “deleted” by the Ender Garbage Bin.
The “Dimension” is literally just a List of uncapped ItemStacks and uncapped Fluid Tanks,
It is extremely unlikely someone would ever bloat a save file with that, since it only ever stores one (up to 2³¹-1 sized) ItemStack per unique Item Type.
So yes, you can retrieve a LOT of things with the Garbage Dump, which is why it is cheat-in only. Afterall it would be an arbitrary Teleporter and Global Item Collector. Imagine just letting Items despawn in order to teleport them Home.