Nix / NixOS

I want to change my hardware config from 2 btrfs partitions to 1 partition with subvolumes for root, /nix, /home, and maybe some other like /log.

I mainly want to optimize the /nix/store. And possibly being ready to integrate the impermanence module down the line

What would be the easiest way to accomplish this without reinstalling or breaking too much?

Alternativly I thought about using disko and nixos-install the overwrite my second disk

Thank you