The presentation that Windows Central got its hands on details how the companies are working on bringing Razer Chroma RGB lighting to Xbox games thanks to the Razer BlackWidow Chroma V2, which would enable visual cues for abilities, for example. This update was supposed to be included in the April 2018 XDK update, which would have meant rollout in the Fall 2018 update. Windows Central was unable to confirm whether it was indeed included or has met some unforeseen delay (or even cancellation)
The presentation also details how some of the implementation would go for developers in terms of integrating mouse and keyboard support into Xbox games. All games must still support gamepad play, and each console can only support one keyboard/mouse. Developers will also be able to tell when users are playing with a keyboard and mouse versus a controller; if they want to separate out these gamers for multiplayer play, they will be able to do so. (The thinking is reaction time is often faster on a keyboard and mouse, which might give players using them an unfair advantage.)
The Xbox will supposedly support all USB mice that can be used with Windows; Bluetooth and custom-driver peripherals will not be supported. Microsoft will also introduce an API that will allow developers to detect users that are taking advantage of peripherals that can mimic controller behavior to gain an advantage.