https://www.theverge.com/2018/11/14/18095086/xbox-one-keyboard-mouse-support-november-update-release

Microsoft is enabling mouse and keyboard support for its Xbox One console today. Fortnite will be one of the first games to enable this support alongside Warframe. Bomber Crew, Deep Rock Galactic, Strange Brigade, Vermintide 2, War Thunder, and X-Morph Defense will also all support keyboard and mouse later this month. Microsoft also previously revealed 7 additional games will support keyboard and mouse in the future.

Developers will need to specifically opt-in to enable keyboard and mouse support in Xbox One games, and Fortnite in particular is only matching these gamers with the same inputs to keep play balanced. Most modern wired or wireless USB keyboards and mice will work on the Xbox One, and Microsoft is also partnering with Razer to launch a wireless mechanical keyboard and mouse set that’s designed for Xbox. Microsoft is promising more news on this at CES in January.