Copy that entire GAMEID folder to a new location. Then, use (freeware) or mkisofs (Linux) to create an ISO.
Several tools have been developed specifically for PS3 PKG to ISO conversion: how to convert pkg to iso 2021
: Use the createinstallmedia tool within the .app bundle to copy all the installation files onto your new disk image. Make sure to replace /Volumes/macOSInstaller and /Applications/Install\ macOS\ Big\ Sur.app with your actual volume name and the exact name of your macOS installer if it differs. Copy that entire GAMEID folder to a new location