The PS4 has a built-in (but hidden) PS2 emulator used for "PS2 Classics."
Many top PS3 games have native PS4 ports: God of War III Remastered , Uncharted: Nathan Drake Collection , The Last of Us Remastered . These are actual PS4 PKG files, not conversions.
Please consider the following:
there is no verified software that can simply convert a PS3 game file (.pkg or ISO) to run natively on a PS4.
The quest for a PS3 to PS4 converter is driven by the desire for backward compatibility, but technical barriers make a simple software converter impossible. Architectural Mismatch : The PS3's Cell Broadband Engine ps3 to ps4 pkg converter verified
Since direct conversion isn't an option, users generally rely on these verified alternatives:
This leads to the primary confusion in the community: The PS4 has a built-in (but hidden) PS2
Given the lack of a verified converter, here are the legitimate alternatives: