How to display travel time in google maps in flutter?

I would like to get the travel time displayed from the JSON data for the current location of the user. At the moment, I only have polylines displayed from the current location to the destination. My code:

import 'package:http/http.dart' as http;
import 'dart:convert';
import 'dart:async';

const apiKey = "xxxxxxx";

  class GoogleMapsServices {
  Future<String> getRouteCoordinates(LatLng l1, LatLng l2) async {
  String url = "https://maps.googleapis.com/maps/api/directions/json?origin=${l1
      .latitude},${l1.longitude}&destination=${l2.latitude},${l2
      .longitude}&mode=walking&key=$apiKey";
  http.Response response = await http.get(url);
  Map values = jsonDecode(response.body);
  print("====================>>>>>>>>${values}");

  return values["routes"]["distance"]["duration"]["overview_polyline"]["points"];

  }
  }```

 List<LatLng> _convertToLatLng(List points) {
    List<LatLng> result = <LatLng>[];
    for (int i = 0; i < points.length; i++) {
      if (i % 2 != 0) {
        result.add(LatLng(points[i - 1], points[i]));
      }
    }
void createRoute(String encondedPoly) {
    _polyLines.add(Polyline(
        polylineId: PolylineId(latLng.toString()),
        width: 4,
        points: _convertToLatLng(_decodePoly(encondedPoly)),
        color: Colors.deepOrange),
    );
  }

List _decodePoly(String poly) {
    var list = poly.codeUnits;
    var lList = new List();
    int index = 0;
    int len = poly.length;
    int c = 0;
    do {
      var shift = 0;
      int result = 0;

      do {
        c = list[index] - 63;
        result |= (c & 0x1F) << (shift * 5);
        index++;
        shift++;
      } while (c >= 32);
      if (result & 1 == 1) {
        result = ~result;
      }
      var result1 = (result >> 1) * 0.00001;
      lList.add(result1);
    } while (index < len);

    for (var i = 2; i < lList.length; i++)
      lList[i] += lList[i - 2];

    print(lList.toString());

    return lList;
  }
Widget _mapWidget() {
    return GoogleMap(
      mapType: MapType.hybrid,
      polylines: polyLines,
      markers: _createMarker(),
      initialCameraPosition: CameraPosition(
          target: latLng, zoom: 12.0),
      onMapCreated: (GoogleMapController controller) {
        _controller = controller;
        _setMapPins();
      },
      onCameraMove: onCameraMove,
      tiltGesturesEnabled: false,
      onTap: (LatLng location) {
        setState(() {
          _pinPillPosition = -100;

          _pinPillPosition2 = -100;
          _polyLines.clear();
        });
      },
    );
  }
    return result;
  }
void sendRequest() async {
    LatLng destination = LatLng(52.523778, 13.405193);
    String route = await _googleMapsServices.getRouteCoordinates(
        latLng, destination);
    createRoute(route);
  }

I would like to have the time and distance displayed in a pill container that pop-ups when a marker is clicked. Thank you in advance.