No functional custom ROM exists. The best you can do is root + debloat + tweak the stock firmware.

adb shell pm uninstall -k --user 0 com.asus.launcher adb shell pm uninstall -k --user 0 com.asus.weathertime # etc.

When you search for a custom ROM for this device, you aren't just looking for a software update; you are looking for a soul transplant.

Do not fall for fake "Android 10 GSI" videos on YouTube for the Z300C. They either do not boot or have broken hardware acceleration.

Remember: Always backup your stock firmware using TWRP before flashing. You can find stock Asus ROMs on their official support site for disaster recovery.

Because it uses an x86-based Intel SoC, standard ARM ROMs will not work. Most development for this device stopped at Android 5.0 or 6.0 . 📉 Performance Review