I was struggeling to do this with my new ROCK 3c, as the documentation on the wiki/radxa websites is totally confusing and missing stuff.
I found this info for rock4 and managed to successfully install os to eMMC after boot from sd-card.
- install os to sd-card
- boot
- download image
- write to EMMC
xzcat rock-your image name img.xz | sudo dd of=/dev/mmcblk-SELCT correct device bs=1M
I believe this works for Rock 5 the same way.
I wonder if it would be possible to clone the current running OS to eMMC like this as well.
@hipboi I think this is a very useful info for many users - maybe you can make this available on the wikis