ServiceListPage.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Threading.Tasks;
using Plugin.BLE.Abstractions.Contracts;
using Xamarin.Forms;


// the goal is to get result of device.GetServicesAsync() into this.services

namespace ClickCount {
    public partial class ServiceListPage : ContentPage {
        ObservableCollection<IService> services = new ObservableCollection<IService>();

        public ServiceListPage(IDevice device) {
            InitializeComponent();
            ServiceList.ItemsSource = services;
            GetServices(device); // raises warning
        }

        private async Task GetServices(IDevice device) {
            services = new ObservableCollection<IService>(await device.GetServicesAsync());
            Console.WriteLine("## Got services::::");
            Console.WriteLine(services);
        }
    }
}