Directly converting a file to a PS4 PKG for native play is generally not possible due to the radical differences in system architecture . The PS3 uses a custom Cell processor , while the PS4 uses an x86-based architecture, making their software instructions incompatible.
For those with a jailbroken PS4, there is a technical method to run PS3 games using the via a Linux payload. ps3 to ps4 pkg top
Sony previously offered a way to "convert" specific games from PS3 to PS4. This wasn't a file conversion, but a digital license upgrade. Directly converting a file to a PS4 PKG
The Ultimate Guide to PS3 to PS4 PKG: Everything You Need to Know Sony previously offered a way to "convert" specific
: Users with a PS3 disc version of a specific game (like Assassin's Creed IV Black Flag ) could redeem a code in the PlayStation Store to buy the digital PS4 version at a heavily discounted price.
While you can't "convert" the game to run on a standard PS4, you might be looking for ways to manage and prepare your PS3 backups using modern PC tools.