https://techcrunch.com/2018/11/10/xbox-one-will-work-with-keyboard-and-mouse-as-of-november-14th-starting-with-fortnite/

We knew the Xbox One was set to get keyboard and mouse support eventually, but now we know exactly when: November 14th.

Don’t expect all Xbox One games to play friendly with the new keyboard/mouse functionality right out of the gate. It’s up to individual developers to figure out if/how it works with their games and patch things up accordingly, so only a handful will support it at first.