Eagle 3D Streaming runs your Unreal Engine application on its own GPU machines and streams it to any browser with Pixel Streaming. These are the guides for getting it there, putting it in your own site, and configuring what viewers get.
You can put your own launcher in front of your Unreal app on Eagle 3D Streaming — an exe that runs first, does whatever you need, and then starts the app.
A Shipping build of an Unreal app writes no log: logging is compiled out, not switched off.
In Unreal Engine the mouse cursor is shown with Show Mouse Cursor on the Player Controller.
Developer options in an Eagle 3D Streaming configuration let you pass values into your app at launch, choose where it runs, and get hold of the logs when something goes wrong.