https://www.cnet.com/news/fortnite-on-xbox-one-gets-mouse-and-keyboard-support-wednesday/

We also got some more details on Microsoft's official Designed for Xbox devices, which include a Xbox keyboard and dynamic lighting. Razer will be the exclusive partner, with more details coming during CES 2019. That mouse and mechanical keyboard combo will also be wireless.

Microsoft first announced mouse and keyboard support would be coming to the console during an Insider livestream earlier this year. As mentioned during that event, said support is entirely reliant on developers choosing to allow it. Any USB mouse and keyboard will be compatible, but not every game will support alternative controls.