semi newb question about pkg extraction

[xokia]

I have a "jailbroken" ps4. I can dump my games and convert them to fPKG. But I have learned I can not update them after that unless I find a fPKG update. Or I uninstall the game from the HDD. Reload the retail game then install the retail update. Then Dump both the game and update and create fPKG of both. With such huge files this can be tedious. Is there a way to extract the normal pkg file. Or is there a way to get the key from the disc dump to use as the passcode I would assume when you go to extract using opis-pub-chk.exe. Sorry if these are dumb questions I am still learning it all.