Try manually caching

.gitea/workflows/build-pi-img.yml

@@ -22,9 +22,28 @@ jobs:
           nix_path: nixpkgs=channel:nixos-23.05
       - name: Remove access_tokens
         run: sed -i '/^access-tokens/d' /etc/nix/nix.conf
-      - uses: https://github.com/DeterminateSystems/magic-nix-cache-action@main
+
+      - name: Cache Nix store
+        uses: actions/cache@v3.0.8
+        id: nix-cache
+        with:
+          path: /tmp/nixcache
+          key: "pi-build-cache"
+
+      - name: "Import Nix store cache"
+        if: "steps.nix-cache.outputs.cache-hit == 'true'"
+        run: "nix-store --import < /tmp/nixcache"
+
+      - name: "Build application"
+        run: "nix build --print-build-logs"
+
       - name: Build image
         run: nix-build '<nixpkgs/nixos>' -A config.system.build.sdImage -I nixos-config=./pi-imgs/pi-initial.nix --argstr system aarch64-linux
       - uses: https://github.com/actions/upload-artifact@v3.1.2
         with:
           path: result/sd-image/*.img
+
+      - name: "Export Nix store cache"
+        if: "steps.nix-cache.outputs.cache-hit != 'true'"
+        run: "nix-store --export $(find /nix/store -maxdepth 1 -name '*-*') > /tmp/nixcache"
+