Hi Insanerob,
This can already be setup at the moment using Blueprints or C++ for mobile. The setup should not be much different than a normal multiplayer game. The biggest hurdle is getting the order of operations right for the setup of a multiplayer networked game.
If you’ve not had a chance to look at the Networking & Multiplayer documentation this should be a good starting point for you: Networking and Multiplayer in Unreal Engine | Unreal Engine 5.1 Documentation
Coming with 4.10 you will have the ability to use multiple controllers with your device for multiplayer from a single device.
There are plans to add a sample in the future to demonstrate this setup using Blueprints and multiplayer setup, but unfortunately I don’t have a time frame for when this will be completed.