diff --git a/overview/content-types/config-item.nix b/overview/content-types/config-item.nix
deleted file mode 100644
index bd05b68a7..000000000
--- a/overview/content-types/config-item.nix
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-  name,
-  config,
-  lib,
-  ...
-}:
-let
-  inherit (lib) mkOption types;
-in
-{
-  options = {
-    name = mkOption {
-      type = types.str;
-      default = name;
-    };
-    value = mkOption {
-      type = with types; either str (listOf str);
-    };
-  };
-}
diff --git a/overview/content-types/nix-config.nix b/overview/content-types/nix-config.nix
deleted file mode 100644
index 726d1126c..000000000
--- a/overview/content-types/nix-config.nix
+++ /dev/null
@@ -1,29 +0,0 @@
-{
-  name,
-  config,
-  lib,
-  ...
-}:
-let
-  inherit (lib) mkOption types;
-in
-{
-  options = {
-    __toString = mkOption {
-      type = with types; functionTo str;
-      readOnly = true;
-      default =
-        self:
-        let
-          separator = "'$'\\n''";
-          concatSettings = lib.concatStringsSep separator (
-            lib.map (attrs: "${attrs.name} = ${toString attrs.value}") self.settings
-          );
-        in
-        "NIX_CONFIG='${concatSettings}'";
-    };
-    settings = mkOption {
-      type = with types; listOf (submodule ./config-item.nix);
-    };
-  };
-}
diff --git a/overview/default.nix b/overview/default.nix
index d7ee0eed8..3b6d20f7d 100644
--- a/overview/default.nix
+++ b/overview/default.nix
@@ -300,31 +300,26 @@ let
             }
           ];
         };
-        nix-config = eval {
-          imports = [ ./content-types/nix-config.nix ];
-          settings = [
-            {
-              name = "substituters";
-              value = [
-                "https://cache.nixos.org/"
-                "https://ngi.cachix.org/"
-              ];
-            }
-            {
-              name = "trusted-public-keys";
-              value = [
-                "cache.nixos.org-1:6nchdd59x431o0gwypbmraurkbj16zpmqfgspcdshjy="
-                "ngi.cachix.org-1:n+cal72roc3qqulxihpv+tw5t42whxmmhpragkrsrow="
-              ];
-            }
-          ];
-        };
-        set-nix-config = eval {
-          imports = [ ./content-types/commands.nix ];
-          instructions.commands.bash.input = ''
-            export ${nix-config}
-          '';
-        };
+        set-nix-config =
+          let
+            from-yaml =
+              file:
+              with builtins;
+              fromJSON (
+                # XXX(@fricklerhandwerk): IFD, sorry. I was there, Gandalf: https://github.com/NixOS/nix/pull/7340
+                readFile (pkgs.runCommandNoCC "yaml.json" { } "${lib.getExe pkgs.yj} < ${file} > $out")
+              );
+            workflow = from-yaml ../.github/workflows/test-demo.yaml;
+            nix-config = with lib; trim (elemAt workflow.jobs.test.steps 3).env.NIX_CONFIG;
+          in
+          eval {
+            imports = [ ./content-types/commands.nix ];
+            instructions.commands.bash.input = ''
+              export NIX_CONFIG="
+              ${nix-config}
+              "
+            '';
+          };
       in
       ''
         ${heading 2 "demo" (