If you cannot find a stable Android 11 build for your specific TV box, the "Proper Feature" for RK3328 is actually running .
: When a green success message appears, disconnect the device and boot it up. The first boot can take 5–7 minutes. Key Performance Benefits of Android 11 on RK3328 CSC Armbian for RK3318/RK3328 TV box boards - Page 27
: A user on the Armbian forums shared a Google Drive link containing original Android 11 firmware for specific RK3328 boards (specifically discussed in the context of X88 boards).