not-os is a small experimental OS I wrote for embeded situations, it is based heavily on NixOS, but compiles down to a kernel, initrd, and a 48mb squashfs

there are also example iPXE config files, that will check the cryptographic signature over all images, to ensure only authorized files can run on the given hardware

and I have Hydra setup and doing automatic builds of not-os against nixos-unstable, including testing that it can boot under qemu