How do I get a Flutter project running on MacOS to successfully use Firestore?

I have a simple Flutter project. All it does is connect to a Firestore collection, pull some documents, and display them. This works fine on iOS. However, when I try to run it in macOS, I'm unable to retrieve the documents. I don't see any exceptions, just the absence of success.

The only things I changed from the initial default project was one of the build methods (below), and importing 'package:cloud_firestore/cloud_firestore.dart'.

My build method:

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: StreamBuilder(
        stream: Firestore.instance.collection('mycollection').snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) return const Text('Loading');
          return ListView.builder(
              itemExtent: 80,
              itemCount: snapshot.data.documents.length,
              itemBuilder: (context, index) => ListTile(
                      title: Row(
                    children: [
                      Expanded(
                        child:
                            Text(snapshot.data.documents[index].data['title']),
                      )
                    ],
                  )));
        },
      ),

      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

From reading around, it seems that macOS is not fully supported by Firebase. That said, it appears people have been able to make it work - for example, Swift macOS Firebase. I've also seen that perhaps I should be using the FirebaseCore pod as opposed to Firebase/Core pod as seen here. While I tried to manually add the FirebaseCore pod, it appears I still have the Firebase/Core pod, and I don't understand how the pubspec/pods mechanism enough yet to pull it out.

More background:

▶ flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel master, 1.21.0-1.0.pre, on Mac OS X 10.15.5 19F101, locale en-US)
[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, set ANDROID_SDK_ROOT to that location.
      You may also want to add it to your PATH environment variable.


[✓] Xcode - develop for iOS and macOS (Xcode 11.6)
[✓] Chrome - develop for the web
[!] Android Studio (not installed)
[✓] VS Code (version 1.47.0)
[✓] Connected device (4 available)

My app was in App Sandbox mode, and didn't have the proper entitlement. I could solve the problem in two different ways:

1. Add the com.apple.security.network.client entitlement to both entitlement files (DebugProfile.entitlements and Release.entitlements, both under macos/Runner. This is the preferred option, if I want to be able to release my app in the App Store.

2. I could turn the App Sandbox mode off by setting the com.apple.security.app-sandbox entitlement to false, again in the same entitlement files.

The problem of being unable to make a network request was masked in my case because the Firestore client defaults to a local cache if it can't reach the cloud. So in my case, the local cache had no data, and I got an empty response as opposed to an error.

See https://flutter.dev/desktop#entitlements-and-the-app-sandbox for more information.