These are packaged by third-party tools. They are not signed by Sony. To install these, you have a PS3 running Custom Firmware (CFW) or PS3HEN (Homebrew ENabler) . These PKGs are typically used for:
DLC PKGs include things like:
Plug the USB into your PS3 and open your file manager (e.g., multiMAN). Ps3 Dlc Pkg Files
The last thing Leo remembered was the amber glow of the TV and the hum of the fat PlayStation 3. It was 2013. He was 16, downloading the Undead Nightmare PKG for Red Dead Redemption via a shaky USB stick because his internet was too slow for the PSN store. These are packaged by third-party tools
Installing DLC via PKG files usually requires a PlayStation 3 running or PS3HEN . Ps3 Dlc Pkg Files