Unless you specifically need ISO 9660 for an optical disc or legacy VM, consider converting to .dmg (macOS native) or .tar.gz (cross-platform) after extraction.
Some games or software (e.g., Yakuza 5 on PS3) are known to fail when converted from PKG to ISO due to specific file modifications required in the eboot or internal structure. how to convert pkg to iso
The tools differ depending on the source of your PKG file (macOS vs. PlayStation). Here is the essential software list: Unless you specifically need ISO 9660 for an