[mschwaig]

This is about right but let me clarify a bit.

The configuration.nix system configuration can be moved between systems, but imports a generated hardware-configuration.nix that really should not be moved between systems.

If you don't want user and system specific configuration to intermix by having user-specific software in your system configuration and you want to manage you the dotfiles in your home directory in the style of Nix there is another popular project called home-manager which enables that, but that's totally optional.