My understanding is that most cheats for retro consoles are a memory location plus a value to write in that location.
I believe that’s how the “game genie” worked on nes, snes, and OG game boy. Have you tried entering some game genie/game shark codes in the RA cheats for your core?
It’s been a while since I used cheats on RA other than save states and rewind but I know I’ve gotten them working before (years ago) on snes
Is the game data actually in the portmaster directory when you browse the SD card on a PC? I know many pm games require copyrighted data to run (half life for example)
A lot of these stock OSes are crudely translated from Chinese perhaps “ready to play” isn’t literal.
I’ve gotten several portmaster games working on ArkOS on my Anbernic devices, check their wiki it’s probably similar to the setup required on the anbernic stock OS