Xbox Keyboard

you can use mouse and keyboard on xbox now, even microsoft sell an xbox keyboard. ps4 is now starting to support mouse and keyboard.

This is incorrect. The XBOX One does support USB keyboards and wireless USB keyboards. I use the Microsoft Media keyboard...

For the following to work you must make the menu selections using your keyboard. If you use the controller to make your menu selections to start the game you will be placed in a room for those with a controller and your keyboard/mouse will be non functional
to make it fair to other players. To enter the room for keyboard and mouse users the game must be started by selecting the options using the keyboard/mouse. Hope this helps.

Mouse and keyboard support

Fortnite on Xbox One supports the ability to play with a mouse and keyboard. Note that when using a mouse and keyboard on Xbox One, you’ll be placed in a game with other users who also chose mouse and keyboard as their control option. To enable your setup
to use mouse and keyboard, see Mouse and Keyboard Support

Note If you’re on a child account, you’ll also need to enable settings for cross-network play to use a keyboard and mouse while playing
on Xbox One.

It is recommended to use Microsoft Wired Keyboard, as wireless adapter for keyboard will interfere with Xbox One's internal wireless adapter for Controllers or WiFi, and Xbox One does not have drivers for keyboard wireless dongle.

Hey there Matt,

Sorry to hear you are running into problems with your Keyboard.

What game exactly is it that you are trying to jump into? Make sure that the game itself supports keyboard and mouse.

Also take a look at the following link for more help with keyboard and mouse support.

Mouse and Keyboard support on Xbox One

I hope this helps.