base/nix.nix

@@ -1,4 +1,4 @@
-{ lib, config, inputs, ... }:
+{ inputs, ... }:
 {
   nix = {
     gc = {
@@ -21,16 +21,11 @@
     ** use the same channel the system
     ** was built with
     */
-    registry = lib.mkMerge [
-      {
-        "nixpkgs".flake = inputs.nixpkgs;
-        "nixpkgs-unstable".flake = inputs.nixpkgs-unstable;
-      }
-      # We avoid the reference to self in vmVariant to get a stable system .outPath for equivalence testing
-      (lib.mkIf (!config.virtualisation.isVmVariant) {
-        "pvv-nix".flake = inputs.self;
-      })
-    ];
+    registry = {
+      "nixpkgs".flake = inputs.nixpkgs;
+      "nixpkgs-unstable".flake = inputs.nixpkgs-unstable;
+      "pvv-nix".flake = inputs.self;
+    };
     nixPath = [
       "nixpkgs=${inputs.nixpkgs}"
       "unstable=${inputs.nixpkgs-unstable}"

base/services/auto-upgrade.nix

@@ -1,4 +1,4 @@
-{ config, inputs, pkgs, lib, ... }:
+{ inputs, pkgs, lib, ... }:
 
 let
   inputUrls = lib.mapAttrs (input: value: value.url) (import "${inputs.self}/flake.nix").inputs;
@@ -26,14 +26,12 @@ in
 
   # workaround for https://github.com/NixOS/nix/issues/6895
   # via https://git.lix.systems/lix-project/lix/issues/400
-  environment.etc = lib.mkIf (!config.virtualisation.isVmVariant) {
-    "current-system-flake-inputs.json".source
-      = pkgs.writers.writeJSON "flake-inputs.json" (
-        lib.flip lib.mapAttrs inputs (name: input:
-          # inputs.*.sourceInfo sans outPath, since writeJSON will otherwise serialize sourceInfo like a derivation
-          lib.removeAttrs (input.sourceInfo or {}) [ "outPath" ]
-            // { store-path = input.outPath; } # comment this line if you don't want to retain a store reference to the flake inputs
-        )
-      );
-  };
+  environment.etc."current-system-flake-inputs.json".source
+    = pkgs.writers.writeJSON "flake-inputs.json" (
+      lib.flip lib.mapAttrs inputs (name: input:
+        # inputs.*.sourceInfo sans outPath, since writeJSON will otherwise serialize sourceInfo like a derivation
+        lib.removeAttrs (input.sourceInfo or {}) [ "outPath" ]
+          // { store-path = input.outPath; } # comment this line if you don't want to retain a store reference to the flake inputs
+      )
+    );
 }

flake.nix

@@ -169,9 +169,9 @@
     };
 
     devShells = forAllSystems (system: {
-      default = nixpkgs-unstable.legacyPackages.${system}.callPackage ./shell.nix { };
+      default = nixpkgs.legacyPackages.${system}.callPackage ./shell.nix { };
       cuda = let
-        cuda-pkgs = import nixpkgs-unstable {
+        cuda-pkgs = import nixpkgs {
           inherit system;
           config = {
             allowUnfree = true;