Since I installed linux (Debian, Armbian or ubuntu) on the hard disk m.2 nvme I can not boot any Android in eMMc, only from the SD.
It would be possible to have double boot, that is to say Android in eMMc and Linux in NVME
ROCK PI 4B 4GB v1.3+ Limited Edition Bundle (incl. mounted 16MB SPI Flash)
Disco Acer de 128 GB