Hi,
If you have the possibilities, make a 'button box' using an Arduino Mega:
Then you are free to customize it the way you want
Or you can buy these 'arcade joystick kit' that have alle the things you need; USB board, buttons and joystick: https://www.aliexpress.com/item/1005006881834466.html
Almost done with the traincontroler for SimRail, based on an Arduino Mega joystick, because it have 52 digital I/O, and if that is not enough there is also a bunch og anaglo inputs
I use JoyToKey to send commands to SimRail