Using a mouse and keyboard on Xbox, PlayStation, or Switch isn't plug-and-play for most games, but several workarounds exist depending on your needs.
Note: These emulate a controller, so the game thinks you're using a pad. Aim assist usually remains active.
If you only play a few supported games natively, use official support. For broad FPS compatibility, a XIM Apex is the gold standard—but research your specific games and the competitive integrity policies first.