You could try
https://arm-files.devuan.org/
There is a rockpro image, the README is the install script
ie,, expand it on hd (and read README, alter for correct device, run it), don't just write to SD
seems to work OK
-----
Note: to put on emmc edit boot.cmd ,, remake image (boot.scr), change fstab (blk2)
-----
and how this image got made....https://github.com/pyavitz/debian-image-builder
Every image i have made (so far) boots
You may well have to tinker with the scripts, if you don't have right OS
https://arm-files.devuan.org/
There is a rockpro image, the README is the install script
ie,, expand it on hd (and read README, alter for correct device, run it), don't just write to SD
seems to work OK
-----
Note: to put on emmc edit boot.cmd ,, remake image (boot.scr), change fstab (blk2)
-----
and how this image got made....https://github.com/pyavitz/debian-image-builder
Every image i have made (so far) boots
You may well have to tinker with the scripts, if you don't have right OS