There are three CFW builds considered "exclusive royalty" for the M3:
Do you need help for the latest beta build or a guide on transferring your own ROMs to the new firmware? sup m3 custom firmware exclusive
: Better performance for Game Boy Advance (GBA) and NES compared to the stock UI. There are three CFW builds considered "exclusive royalty"
No firmware is perfect, and there are caveats to consider before flashing. sup m3 custom firmware exclusive
Yes. You cannot get these features on the Anbernic, PowKiddy, or Miyoo devices. The developer (known only as "NeoLag") specifically coded the shader engine and the cloud sync script for the Sup M3’s unique Allwinner F1C200s chipset. Because the source code is closed, no other device has replicated the that runs GBA games at 2x speed without audio crackling.