Try re-enabling system.autoUpgrade with the "boot" operation

configuration/Legion.nix

@@ -1,4 +1,4 @@
-{config, ...}: {
+{...}: {
   imports = [
     ../services/caddy.nix
     ../services/forgejo.nix
@@ -16,12 +16,10 @@
   };
   users.mutableUsers = false;
   system.autoUpgrade = {
-    enable = true;
+    operation = "switch";
-    flake = "git+${config.nix.registry.my-nixos.to.url}";
-    dates = "02:00";
     allowReboot = true;
     rebootWindow = {
-      lower = "02:00";
+      lower = "01:00";
       upper = "05:00";
     };
   };

configuration/default.nix

@@ -1,4 +1,5 @@
 {
+  config,
   pkgs,
   iosevkaCustom,
   ...
@@ -26,7 +27,21 @@
     '';
   };
   nixpkgs.config.allowUnfree = true;
-  system.stateVersion = "23.05";
+  system = {
+    stateVersion = "23.05";
+    autoUpgrade = {
+      enable = true;
+      persistent = true;
+      flake = "git+${config.nix.registry.my-nixos.to.url}";
+      dates = "02:00";
+      randomizedDelaySec = "45min";
+      flags = [
+        "--option"
+        "extra-binary-caches"
+        "https://nix.xenia.me.uk"
+      ];
+    };
+  };
   boot.loader = {
     systemd-boot.enable = true;
     efi.canTouchEfiVariables = true;

configuration/desktop.nix

@@ -5,6 +5,7 @@
 }: {
   imports = [./default.nix];
   nixpkgs.config.chromium.commandLineArgs = "--enable-features=UseOzonePlatform --ozone-platform=wayland";
+  system.autoUpgrade.operation = "boot";
   environment = {
     sessionVariables = {
       NIXOS_OZONE_WL = "1";