While Lightstream doesn't offer traditional scene transitions, you can accomplish a "Stinger" like effect by uploading a video file that contains your transition animation.
First thing you’ll need to do is add a video file containing your transition to your project.
Once added to your scene, you will need to adjust the playback settings of the video clip to create the scene (stinger) transition effect.
While your video file is selected in your scene, use the more settings drop-down menu to change the “When video ends” option to the “Stop & Hide” setting. This will cause the video to play a single time on your channel upon switching to the scene. Then once the video has finished playing on your channel, it will automatically be hidden from your scene.
Note: The preview of the video layer in the center canvas will show on “Loop” by default, regardless of your “When video ends” setting. This is to allow you to properly line things up before going live, but will not affect your stream itself.