misc general changes / nixpkgs break fixes

modules/core/default.nix

@@ -1,14 +1,23 @@
-{ inputs, pkgs, ... }: {
+{ inputs, lib, pkgs, ... }: {
   boot.loader = {
     systemd-boot.enable = true;
     efi.canTouchEfiVariables = true;
   };
 
-  nixpkgs.config.allowUnfree = true;
+  nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
+    "osu-lazer-bin"
+    "unrar"
+    "steam"
+    "steam-original"
+    "corefonts"
+    "vista-fonts"
+    "steam-unwrapped"
+  ];
 
   nixpkgs.config.permittedInsecurePackages = [
-    "electron-24.8.6"
-    "electron-25.9.0"
+    "jitsi-meet-1.0.8043"
+    "electron-28.3.3"
+    "electron-27.3.11"
   ];
 
   documentation = {
@@ -25,8 +34,10 @@
   ];
 
   nix = {
-    # hardlink duplicate files in the nix store
-    settings.auto-optimise-store = true;
+    settings = {
+      # hardlink duplicate files in the nix store
+      auto-optimise-store = true;
+    };
 
     extraOptions = ''
       experimental-features = nix-command flakes
@@ -34,6 +45,8 @@
       # keep intermediary deps alive (no redownloading to rebuild after gc)
       keep-outputs = true
       keep-derivations = true
+
+      builders-use-substitutes = true
     '';
 
     # flake registries are used by the new nix commands.
@@ -49,6 +62,18 @@
       "nixpkgs=/etc/nix/inputs/nixpkgs"
       "stable=/etc/nix/inputs/stable"
     ];
+
+    distributedBuilds = true;
+    buildMachines = [ {
+      hostName = "192.168.2.1";
+      system = "x86_64-linux";
+      protocol = "ssh-ng";
+      supportedFeatures = [ "big-parallel" "kvm" "nixos-test" "benchmark" ];
+      speedFactor = 100;
+      maxJobs = 16;
+      sshUser = "nix-remote-build";
+      sshKey = "/root/.ssh/id_build_server";
+    } ];
   };
 
   # add entries for `nixPath` above.