Looking for basic, Google Pixel like experience on your Samsung Galaxy A12 smartphone?
This Galaxy A12 ROM will let you do that. This will require you to have TWRP, a custom recovery that would let you flash 3rd party ROMs and firmwares.
In ODIN, select recovery.img in AP slot, and nulled VBMETA.img (below) in USERDATA slot. Make sure AUTO REBOOT is OFF.
Here is a step by step guide on how to download and flash AOSP ROM for Samsung Galaxy A12.
Let ODIN flash all. Once all succeeded; Hold + to shut down, then Hold + to reboot to A12’s TWRP
Once TWRP has booted, do full factory reset – wipe caches and data). After that, format data completely. Reboot to recovery once done.
Once TWRP has re-booted, go to advance, terminal and execute command: multidisabler. This will protect data partition from becoming encrypted again, and secure recovery partition from being replaced.
Reboot to system, and setup device as normal. After this, you could install Root or what ever you want. Everything is working as expected. The only thing not working is ADB sideloading.