How do I Query Firebase Firestore for a field of type Geopoint in Flutter?

Question

I am querying a firestore collection for documents inside of a latitude and longitude range. Since it appears you can't conduct a query with arguments given to two different fields ('lat', 'lon'), I have assigned a type Geopoint to a single field 'coords' that has the longitude and latitude. How do I use .where() with geopoints? Below is the general query I would like to use, where _latMin, _latMax, etc. are variables linked to the bounding box of my map.

_getDocs() async {
  print('getdocs');
  final QuerySnapshot snapshot = await FirebaseFirestore.instance
      .collection('collectionName')
      .where(
        'coords',
        isGreaterThan: _latMin,
        isLessThan: _latMax,
      )
      .where(
        'coords',
        isGreaterThan: _lonMin,
        isLessThan: _lonMax,
      )
      .get();
  snapshot.docs.forEach((DocumentSnapshot doc) {
    print(doc.data());
  });
}

How Do I reference the latitude and longitude inside of coords?