Directly stated, you cannot natively convert a PS3 game into a PS4 PKG (Package) file to install and play directly on a PlayStation 4.
due to the fundamental differences in hardware architecture between the two systems. The PS4 cannot natively execute code designed for the PS3's Cell processor.
If your goal is to play PS3 PKG files, the most effective method is using a PC. ps3 to ps4 pkg install
For those without a jailbroken console, Sony provides official but non-native ways to play these titles:
This method requires booting your PS4 into a Linux environment to run the RPCS3 emulator. Requirements: A jailbroken PS4. A bootable USB stick with Gentoo Linux (DRO). RPCS3 emulator for Linux. PS3 System Software (Firmware). Directly stated, you cannot natively convert a PS3
While the results can be impressive, this is strictly for advanced users with exploited (jailbroken) consoles.
Preparation: You need a jailbroken PS4 (typically firmware 5.05 or 9.00), a USB hub with a keyboard and mouse, and a Linux-ready USB drive. Log your console ID
If you saw a tutorial or tool claiming “install PS3 PKG on PS4,” it is fake, a scam, or mislabeled (it might actually mean converting a PS3 game to run as a PS2 Classic style — which doesn’t work for PS3 games).