The only essential part of your setup is the mouse in a first person shooter. The other input devices are nowhere near as important. Pick whatever you are most comfortable with to complement your mouse: keyboard, controller, joystick, pedals, etc…
Some games (especially older ones) don’t support certain input device combinations due to bad/outdated implementations. That’s usually the only limitation.
Analogue stick VS keyboard have their own pros and cons in case of movement. In most first person shooters keyboard comes out on top due to easy ADAD but OW has quite a few heroes that can benefit a lot from an analog stick.