Flutter Bluetooth printing to Zebra

I need to add printing functionality on a zebra zq520 bluetooth thermal printer. I manage to do so using the flutter_blue plugin and the code below but I am not happy with the implementation. I hate to break the string to smaller chunks in order to pass through bluetooth (and wait!!!!!). I also may need a better regular expression, but that is by far second!

I was wondering if there is a better approach, like the one we used in the (good?) old days of java for android using the android.bluetooth.BluetoothAdapter class

Thanks.

FlutterBlue flutterBlue = FlutterBlue.instance;

bool printOnZebra(String str)  {
  BluetoothDevice _zebra;


 flutterBlue.scan(timeout: Duration(seconds: 4)).listen((scanResult) async {
    BluetoothDevice dev = scanResult.device;
    if (dev.name.startsWith("zebra")) {
      flutterBlue.stopScan();
      _zebra = dev;
      await _zebra.connect();
      List<String> lst = [];

      RegExp exp = new RegExp(r".{" + zebraLen.toString() + "}");
      Iterable<Match> matches = exp.allMatches(str);
      matches.forEach((m) => lst.add(m.group(0)));

      String finalPart = str.substring(lst.length * zebraLen);
      lst.add(finalPart);

      List<BluetoothService> services = await _zebra.discoverServices();


      services.forEach((service) {
        List<BluetoothCharacteristic> blueChar = service.characteristics;
        blueChar.forEach((f) {
          if (f.uuid
              .toString()
              .compareTo("38eb4a82-c570-11e3-9507-0002a5d5c51b") ==
              0) {
            lst.forEach((_str) {
              f.write(utf8.encode(_str));
              sleep(new Duration(milliseconds: zebraWait));
            });
          }
        });
      });

      _zebra.disconnect();


    }

  });
  return true;
}

For those wondering ... the printer's name on the installation site always starts with zebra, that's why I stop discovery after that