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.
