At https://wiki.radxa.com/Rock5/install/spi 3 different versions of the SPI flash image are provided. What are the differences between the radxa and armbian bootloader versions? In other words, how does the armbian image differ from the radxa image such that it requires a different bootloader?
No idea, but looking on that page, the debug image references a Git revision (3caf61a44c2) that’s not found in Radxa’s u-boot repo. (The release build’s sources are fine.)