Support running generate-hardware-config with kexec without a flake

[n0rad]

Prerequisites

• I have searched existing issues to make sure this isn't a duplicate
• I have checked the documentation to see if this feature already exists

Problem Description

👋 , I would like to self identify the nixosConfiguration's name based on the device facts.
To do so I planned to run --generate-hardware-config with the kexec phase to get the facter.json, identify the system, then run the remaining phases.

But currently I have to use a dummy system because a flake is required.

That would be great, if the kexec phase could be run without the flake, I think at this stage a system is not necessary.

Proposed Solution

--phase kexec do not require --flake

Alternatives Considered

No response

Feature Type

New command-line option

Use Case

No response

Implementation Ideas

No response

Additional Context

No response

[Mic92]

It's possible to pass store paths: https://github.com/nix-community/nixos-anywhere/blob/main/docs/howtos/use-without-flakes.md#5-build-and-deploy-with-nixos-anywhere
So maybe dummy store paths could be passed to simplify it?