DeX needs to have a touch overlay built into it so you can assign mouse/KB or gamepad input to on-screen functions. This already exists on a number of different devices, including a couple of apps for third-party controllers, so it's not like Samsung can't do it.
Unfortunately, most good options on the Play Store or apk market either require root or require a third-party controller to be connected. Having this as a native part of OneUI/DeX would be the ideal. It would definitely go a long way toward completing the DeX experience and legitimizing mobile gaming.
Imagine being able to sit down with DeX and play CoD: Mobile with a keyboard and mouse. The experience would be almost indistinguishable from desktop gaming.
just re posting old poste han hope the can fix this i am useing samsung galaxy s22 ultra i realy want key mapping for gaming in samsung dex on my Phone.