If you are referring to standard Apple installer files, you do not need a special "viewer" app. You can use the built-in option in the macOS installer to see what will be installed before you run it. Alternatively, the command-line tool pkgutil --expand file.pkg output_folder can be used to unpack them.
A (often specifically PS4 PKG Viewer ) is a utility used to inspect and verify the contents of .pkg files, which are the standard package format for PlayStation software. It is a critical tool for the homebrew and jailbreak community to ensure that game backups, updates, and DLC are compatible with each other before installation. Key Features PKG Viewer
: Checks if a package is a "Fake PKG" (fPKG) or an official retail package. If you are referring to standard Apple installer