Unfortunately, that post, and everything else I could find during a few minutes searching online, seemed to suggest that the way to do this invariably involves some minor C++ coding. I know this isn’t very helpful, so I’ll leave it as a comment and hope that someone else comes along to prove me wrong!
The simplest solution is to use App And Gamepad Utils plugin from UE Marketplace: pause the game when gamepad is disconnected or game is minimized. It expose C++ function to do that in blueprint where you bind your event, see attached blueprint.