DietPi Image from Debootstrap

Is there a way to to make an image with DietPi without booting the SBC and running the install script on top of it?

Yes, we have a script that is running on GitHub actions creating all our images. But it’s not well documented as main purpose is to build our own images

After going through the build script code I realized that the NanoPi R5S uses a premade image that’s hosted on the dietpi website. Couldn’t find anything on how that base image was built though

Indeed, though I’m about to switch to kernel and bootloader builds from Armbian, skipping those base images.

Those base images are the original Debian images from FriendlyELEC, just with the rootfs removed. The 7 partitions contain the different stages of the bootloader, env, kernel and dtb.