Microsoft has confirmed that keyboard and mouse support will be coming to the Xbox One on the 14th of November. However there is a catch and that is while support will be rolling out next week, only insiders will be able to take advantage of the feature, at least for now, and not all games will support the feature out of the box as it will require them to implement it (if they choose to do so).
It also appears that Epic’s Fortnite Battle Royale will be one of the first few titles to support the new input methods. Now there have been some who have complained about how keyboard and mouse controllers give players an unfair advantage over those who use gamepads, but in this case Epic will match keyboard/mouse players with other similar players, so at the very least everyone will be on the same level in terms of input method.
In terms of titles that will support keyboard and mouse at the start, this includes Vermintide 2, War Thunder, Strange Brigade, Bomber Crew, and Deep Rock Galactic, along with Fortnite.