[devbox] Pass pkgs-unstable.

flake.nix

@@ -181,6 +181,9 @@
       # For machines that don't run NixOS.
       devbox = home-manager.lib.homeManagerConfiguration {
         pkgs = nixpkgs.legacyPackages."x86_64-linux";
+        extraSpecialArgs = {
+          pkgs-unstable = pkgs-unstable_x86_64-linux;
+        };
         modules = [
           ./users/devbox/home.nix
         ];

users/devbox/home.nix

@@ -12,6 +12,11 @@
     ../../home-modules/tmux.nix
   ];
 
+  nvim = {
+    enable = true;
+    package = pkgs-unstable.neovim;
+  };
+
   home = {
     username = "jmug";
     homeDirectory = "/home/jmug";