Change:
<ins> { lib, stdenv, electron, yarn, fixup-yarn-lock, fetchFromGitHub, fetchYarnDeps, nodejs, typescript, makeWrapper, makeDesktopItem, copyDesktopItems, }: let electronDist = electron + (if stdenv.isDarwin then "/Applications" else "/libexec/electron"); in # NOTE mqtt-explorer has 3 yarn subpackages and uses relative links # between them, which makes it hard to package them via 3 `mkYarnPackage` # since the resulting `node_modules` directories don't have the same structure # as if they were installed directly. Hence why we opted to use a # `stdenv.mkDerivation` instead. stdenv.mkDerivation rec { # NOTE official app name is `MQTT-Explorer` but to suffice nixpkgs conventions # we opted to use `mqtt-explorer` instead. pname = "mqtt-explorer"; version = "0.4.0-beta.6"; src = fetchFromGitHub { owner = "thomasnordquist"; repo = "MQTT-Explorer"; rev = "v${version}"; hash = "sha256-oFS4RnuWQoicPemZbPBAp8yQjRbhAyo/jiaw8V0MBAo="; }; offlineCache = fetchYarnDeps { yarnLock = "${src}/yarn.lock"; hash = "sha256-yEL6Vb1Yry3Vns2GF0aagGksRwsCgXR5ZfmrDPxeqos="; }; offlineCacheApp = fetchYarnDeps { yarnLock = "${src}/app/yarn.lock"; hash = "sha256-4oGWBXZHdN+wSpn3fPzTdpaIcywAVdFVYmsOIhcgvUE="; }; offlineCacheBackend = fetchYarnDeps { yarnLock = "${src}/backend/yarn.lock"; hash = "sha256-gg6KrcQz7MdIgFdlbuGiDf/tVd7lSOjwXFIq56tpaTc="; }; nativeBuildInputs = [ nodejs yarn typescript fixup-yarn-lock makeWrapper ] ++ lib.optionals (!stdenv.isDarwin) [ copyDesktopItems ]; env.ELECTRON_SKIP_BINARY_DOWNLOAD = "1"; # disable code signing on macos # https://github.com/electron-userland/electron-builder/blob/77f977435c99247d5db395895618b150f5006e8f/docs/code-signing.md#how-to-disable-code-signing-during-the-build-process-on-macos postConfigure = lib.optionalString stdenv.isDarwin '' export CSC_IDENTITY_AUTO_DISCOVERY=false ''; configurePhase = '' runHook preConfigure # Yarn writes cache directories etc to $HOME. export HOME=$TMPDIR fixup-yarn-lock yarn.lock yarn config --offline set yarn-offline-mirror $offlineCache yarn install --offline --frozen-lockfile --ignore-engines --ignore-scripts --no-progress pushd app fixup-yarn-lock yarn.lock yarn config --offline set yarn-offline-mirror $offlineCacheApp yarn install --offline --frozen-lockfile --ignore-engines --ignore-scripts --no-progress popd pushd backend fixup-yarn-lock yarn.lock yarn config --offline set yarn-offline-mirror $offlineCacheApp yarn install --offline --frozen-lockfile --ignore-engines --ignore-scripts --no-progress popd patchShebangs {node_modules,app/node_modules,backend/node_modules} cp -r ${electronDist} electron-dist chmod -R u+w electron-dist runHook postConfigure ''; buildPhase = '' runHook preBuild tsc && cd app && yarn --offline run build && cd .. yarn --offline run electron-builder --dir  -c.electronDist=electron-dist  -c.electronVersion=${electron.version} runHook postBuild ''; installPhase = '' runHook preInstall ${lib.optionalString (!stdenv.isDarwin) '' mkdir -p "$out/share/mqtt-explorer"/{app,icons/hicolor} cp -r build/*-unpacked/{locales,resources{,.pak}} "$out/share/mqtt-explorer/app" for file in res/appx/Square44x44Logo.targetsize-*_altform-unplated.png; do size=$(echo "$file" | sed -n 's/.*targetsize-([0-9]*)_altform-unplated.png/1/p') install -Dm644  "$file"  "$out/share/icons/hicolor/''${size}x''${size}/apps/mqtt-explorer.png" done makeWrapper '${electron}/bin/electron' "$out/bin/mqtt-explorer"  --add-flags "$out/share/mqtt-explorer/app/resources/app.asar"  --add-flags "''${NIXOS_OZONE_WL:+''${WAYLAND_DISPLAY:+--ozone-platform-hint=auto --enable-features=WaylandWindowDecorations}}"  --set-default ELECTRON_FORCE_IS_PACKAGED 1  --set-default ELECTRON_IS_DEV 0  --inherit-argv0 ''} ${lib.optionalString stdenv.isDarwin '' mkdir -p $out/{Applications,bin} mv "build/mac/MQTT Explorer.app" $out/Applications makeWrapper "$out/Applications/MQTT Explorer.app/Contents/MacOS/MQTT Explorer"  $out/bin/mqtt-explorer ''} runHook postInstall ''; doCheck = true; checkPhase = '' export ELECTRON_OVERRIDE_DIST_PATH=electron-dist/ yarn test:app --offline yarn test:backend --offline unset ELECTRON_OVERRIDE_DIST_PATH ''; desktopItems = [ (makeDesktopItem { name = pname; exec = meta.mainProgram; icon = "mqtt-explorer"; desktopName = "MQTT Explorer"; genericName = "MQTT Protocol Client"; comment = meta.description; type = "Application"; categories = [ "Development" "Utility" "Network" ]; startupWMClass = "mqtt-explorer"; }) ]; meta = with lib; { description = "An all-round MQTT client that provides a structured topic overview"; homepage = "https://github.com/thomasnordquist/MQTT-Explorer"; changelog = "https://github.com/thomasnordquist/MQTT-Explorer/releases/tag/v${version}"; license = licenses.cc-by-nd-40; maintainers = with maintainers; [ tsandrini ]; platforms = electron.meta.platforms; mainProgram = "mqtt-explorer"; }; } </ins>

Discussion:
Project description <!-- Describe the project a little: --Metadata homepage URL: https://mqtt- source URL: license: creative commons platforms: linux, darwin Add a :+1: [reaction] to [issues you find important]. [reaction]: [issues you find important]:
AppImage works fine with appimage-run. There is also a deb and snap package
I use this one
That package looks great. Maybe even worth to try to contribute to nixpkgs.
Unfortunately I don't think the appImage version would be accepted since the source code is available with a build manual so imho a PR to nixpkgs would need to be with a source build. I might look into it
I maybe have a potentially working version. I'll try to find some macs to test out the Darwin versions and if that's gonna be okay I'll then submit a PR
Great news, I can test on darwin.