The CAT skid steers use the electronics over hydraulic joystick controls. This is what I have on my CAT 216 SSL. I have never seen a better control. It feels just like a computer joysick and soon the controls feel more like an extension of your hands.
I have never used an electronic over hydraulic valve that wasn’t proportional like the others were talking about. My CAT controls are totally variable.
I’m sure CAT would sell you all the parts for this system but it would be a major project and modification to adapt these valves, electronics, and joystick to a different tractor. I would suggest doing a search on the web for hydraulic joystick. I did this once upon a time and found several out there. Some were conventional and others were electronic over hydraulic.
Eric