And the winner is... Stylet!

src/Artemis.UI/ViewModels/HomeViewModel.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Diagnostics;
+using Artemis.UI.ViewModels.Interfaces;
+using Stylet;
+
+namespace Artemis.UI.ViewModels
+{
+    public class HomeViewModel : Screen, IMainViewModel
+    {
+        public string Title => "Home";
+
+        public void OpenUrl(string url)
+        {
+            // Don't open anything but valid URIs
+            if (Uri.IsWellFormedUriString(url, UriKind.RelativeOrAbsolute))
+                Process.Start(url);
+        }
+    }
+
+    public interface IMainViewModel : IArtemisViewModel
+    {
+    }
+}