I would have liked perhaps a more distribution agnostic method of running NVMe-TCP in a way that the OS would not have to be booted.

From the pull request:

This all requires that the target mode stuff is included in the initrd of course. And the system will the stay in the initrd forever.

I think that’s as minimal a boot target as you can reasonably get, or in other words you’re as far away from booting the OS as you can get.

So now the question is whether this uses any systemd-specific interfaces beyond the .service and .target files. If not, it should not take much effort to create a wrapper init script for the executable and run it on non systemd distros.