I downloaded 'Armbian_25.11.2_Odroidc2_trixie_current_6.12.58_minimal.img.xz', flashed it to sdcard, and it booted fine.
As a sidenote unrelated to the issue at hand, my first try was with the sdcard on a device with emmc, and in this case the boot process stopped after block-local (?), and dropped to initramfs shell prompt.