Even with all tricks, expect no game to run as well as on real PS3 hardware. This is a hobbyist project, not a commercial solution.
pkg_ps4.exe --fake CUSA12345.gp4
However, the technical reality is more complex than a simple file conversion. Here is everything you need to know about the current state of PS3 games on PS4 hardware. 1. Can You Directly Convert PS3 Games to PS4 PKGs? ps3 to ps4 pkg
Attempting to interact with PKG files outside the official PlayStation Store requires a "jailbroken" or modified PS4. This usually involves: Even with all tricks, expect no game to