For older images balbes150 offers with uEnv.txt, such as Armbian_20.06.0_Arm-64_buster_current_5.7.2_20200619.img.xz, I can always boot from USB no matter what's been installed on the emmc. This is extremely useful because I can easily restore emmc to original Android using ddbr.
However, when it comes to the newer images without uEnv.txt, such as Armbian_20.10_Arm-64_bullseye_current_5.9.0.img.xz, everything changed. I cannot boot from usb anymore unless the system on emmc is original Android. I've been seeking for solution since April 2021 but no answer could be found by now.
zhuceluntan got a reaction from Rulee in Boot from USB having Armbian on eMMC