These are digital installers used for PSN games. They are typically installed through the "Install Package Files" menu on custom firmware (CFW) or HEN-enabled consoles.
The Boletaria Reborn Graphics Pack and LumaSharpen shaders help clear up the original 720p blurriness.
For those seeking to play Demon's Souls without breaking the bank or resorting to piracy, there are legitimate alternatives. The game has been re-released as part of the PlayStation Plus Classics line and is available for purchase on newer consoles like the PlayStation 5, often with enhanced graphics and performance.
See the foundation that led to Dark Souls, Bloodborne, and beyond. How to Get and Play Demon’s Souls