Another option is to run it ephemerally from the RAM. I have been doing this for my laptop and servers for years now. You can do so by declaring the following: https://github.com/ponkila/HomestakerOS/blob/main/nixosModul...

You need to then have a flake which defines a "package" like this: https://github.com/jhvst/nix-config/blob/main/flake.nix#L117...

Now you can run 'nix build .#starlabs' which will create you the files needed for kexec / PXE booting.

You can also write tests that these images actually boot ok: https://discourse.nixos.org/t/nixostest-with-flake-configura...

I started working on this stuff because I needed to somehow reliably update my homeserver. I live abroad 50 weeks a year, so I needed something reliable because I can't assume I have physical access to the computer. Even when the BMC firmware got screwed by ASRock motherboard firmware, I didn't need to sweat.

Now for the shameless plug: my company created a PXE server module which also supports flakes that assumes this ephemeral setup. It's described in here: https://github.com/majbacka-labs/nixos.fi