How do I write 2 records to Firestore and a node in Realtime Database in 1 transaction?

Question

I have 3 functions, shown below. I need either all of them to work or none of them to work, otherwise the data would be messy and I would need to run a cloud function on some frequency to do cleanup, which I'd like to avoid.

The reason I can't use a trigger to run the next function in sequence is because my app needs to know when the 2 functions have been completed before switching the user to a different screen. If I switch the user to another screen while a trigger is completing the background work in some unknown amount of time, I get errors on the client side. So I need to know when this background work has been completed.

I know that Firestore and Realtime Database have transactions, but how would I use both of these together from the client side (Flutter)? If the 3rd function fails, I would need to rollback the work of the first two functions and show the user an error message. Is this possible?

Firestore Function 1:

Future<String> createGroupFS({required String groupName, required String groupSlogan}) async {
    await globals.userGlobals(); //Required if using globals
    final timestamp = getFirestoreTimestamp();
    FirebaseFirestore firestore = FirebaseFirestore.instance;
    final mainGroupsCollectionPath = globals.mainGroupsCollection();

    final newGroupDoc = firestore.collection(mainGroupsCollectionPath).doc();

    var groupID = newGroupDoc.id;
    final adminUID = globals.currentUID;
    final adminUsername = globals.currentUsername;

    final data = ModelMainGroup(
        groupID: groupID,
        groupName: groupName,
        adminUID: adminUID,
        adminUsername: adminUsername,
        createDate: timestamp,
        creatorUID: adminUID,
        creatorUsername: adminUsername,
        initialGroupCreate: true,
        fireTriggers: true,
    ).toJson();

    newGroupDoc.set(data).onError((error, stackTrace) {
      groupID = '';
      return groupID;
    });

    //Add current user as the first member
    final mainGroupMembersCollectionRef = globals.mainGroupMembersCollection(groupID: groupID);
    final mainGroupMembersDocRef = firestore.collection(mainGroupMembersCollectionRef).doc(globals.currentUID);

    final membersData = ModelGroupMember(
        username: adminUsername,
        dateAdded: timestamp
    ).toJson();

    mainGroupMembersDocRef.set(membersData);

    return groupID;
  }

Firestore Function 2:

Future<void> addGroupToCollection({required String groupID}) async {
    await globals.userGlobals(); //Required if using globals
    final groupsCollectionPath = globals.groupsCollection();
    FirebaseFirestore firestore = FirebaseFirestore.instance;

    final newDoc = await firestore.collection(groupsCollectionPath).doc(groupID).get();

    if (newDoc.exists) {
      return;
    }

    final timestamp = getFirestoreTimestamp();
    final data = ModelGroup(dateAdded: timestamp).toJson();

    await firestore.collection(groupsCollectionPath).doc(groupID).set(data);
  }

Realtime Database Callable:

Future<Map<String, dynamic>> createGroupRTDB ({required String groupID, required String adminUID, required String adminUsername}) async {
    //Callable that does the RTDB group setup
    Map<String, String> createdTimestamp = getRTDBTimestamp();
    Map<String, dynamic> returnData = {};

    Map<String, dynamic> parms = {
      'groupID': groupID,
      'adminUID': adminUID,
      'adminUsername': adminUsername,
      'createdTimestamp': createdTimestamp,
    };

    try {
      final callResult = await FirebaseFunctions.instance.httpsCallable('callGroupRTDBSetup').call(parms);

      returnData = {
        'returnVal': 1,
        'returnMsg': '',
      };
    } on FirebaseFunctionsException catch (e) {
      returnData = {
        'returnVal': 0,
        'returnMsg': e.toString(),
      };
    } catch (e) {
      returnData = {
        'returnVal': 0,
        'returnMsg': e.toString(),
      };
    }

    return returnData;
  }