Waiting for stream to stop before returning List - flutter

Question

So I have a StreamSubscription that correctly reads data received from my device.
StreamSubscription<List<int>> _rxSubscription;
List<List<int>> _response = new List<List<int>>();
_rxSubscription = _ble.subscribeToCharacteristic(_rx).listen((event) {
_response.add(event);
});
writeToDevice(List<int> command) async {
_rxSubscription.resume();
await _ble.writeCharacteristicWithoutResponse(_tx, value: command);
return _response;
}
Here is how the device responds:
I/flutter ( 5506): [[0, 65, 0, 0], [0, 0, 104, 220, 69, 91, 240, 63, 0, 0, 240, 100, 112, 209, 240, 63, 0, 0, 176, 19], [133, 233, 240, 63, 0, 0, 104, 126, 172, 204, 240, 63, 0, 0, 96, 250, 189, 193, 240, 63]]
This data is continuously streamed when any write operation is performed and can vary in length depending on the 'command' meaning there can be n number of packets which are sent back. Right now after running the function, it returns an empty list of lists since _response is returned before the device starts responding.
What I'm trying to do: Get the _response to return only after all the data is collected and the device stops responding, ie. the Stream stops streaming. How would I do this in dart? I don't want to use a timer, since the data might take longer or shorter.
(Currently there is no implementation in the packets which might indicate end of line of end of message)
Vendor Instructions:

Answer 1

What I'm trying to do: Get the _response to return only after all the data is collected and the device stops responding, ie. the Stream stops streaming.
Depending on the listener's needs, this may be simplified by using a Future. Is this a broadcast stream?