For many K004 power users, ports derived from the LegacyXperia project were the gold standard in 2021.
# Prerequisites: Intel USB drivers, fastboot from Android SDK platform-tools
adb reboot bootloader
fastboot boot twrp-3.2.3-0-me372cg.img # Only boot, never flash
Inside TWRP:
Flashing the ROM is only half the battle. To make the Asus Fonepad K004 usable in the modern era, users relied on specific tweaks: asus fonepad k004 custom rom 2021