If you own an eligible PS4 disc, you can often download the PS5 digital PKG version for free or a small fee.

If you are interested in the technical side of PS5 exploits and how PKGs work, you should follow reputable developers like SpecterDev

With existing exploits, you will only be playing PS4 games on your PS5. True PS5 native PKG files are not installable publicly.

on social media, as they are the primary sources for legitimate console security research. for PS5 homebrew or how to check your console's version