you could install a normal DietPi system, customize it on your needs and install reqired software. Once done, you could use our image creation tool. This would require to place your SD card on a different system to be able to create the image.
Not sure how PXE is working for rock64. But at least on a Raspberry Pi you are not loading an image file if you boot from PXE. It’s a file server sharing the mounts via NFS. And these NFS mounts are mounted into boot and root file system, where the system is booted from.
On the PXE server you need to store the entire file system per SBC. Usually each device has it’s own directories. They are mounted via NFS on the device during boot. The file system is not copied, it is mounted from a NFS server.
Aa ok so lets say i get 11 Rock 64 one is pxe server and each of the rocks use 2gb so i Would need min of 20 GB storage plus what the system on pxe server and have and 10% free disk space and so and so on
Theoretically you could clone data directory on the PXE server into new one. Usually the different devices should be identified by serial numbers. Just ensure not using any Static IPs. otherwise each device will start with same IP causing conflicts
Just do a test with a first device to get a feeling on how it is working.
This thread on redit says something about having just the /boot directory on an SD card, once booted it then uses USB HD for the rest of the / directory