I flashed my Radxa Rock Pi 4 SPI with Armbian mainline u-boot (I
could not get it up and running with Fedora u-boot) and now I can boot Fedora ARM images
from USB and NVMe seamlessly.
Unfortunately, I am not able to boot from a USB stick created from the workstation ISO
image (I want to try the installation feature to make non-US configuration easier). No
boot media found. Is there no u-boot used or is it due to incompatible implementations?
It depends on what options Armbian use for their U-Boot builds, I
don't know what version they use, whether it's a recent upstream
version or some vendor variant. You'll need to provide more details.
You say you couldn't get it up and running with Fedora's U-Boot but
you provide no details.
You'll need to provide more details and I'd sooner try and work out
the issues with the Fedora U-Boot TBH than try and debug what Armbian
is doing to theirs.
Peter