GCU is capable of reading any data required to run the setup from CAN bus or analog inputs. This means, that if you have a PPS, MAP sensor, Engine RPM on CAN bus, you can read them, and use them in GCU tune, or just connect analog signals directly.
Also there are options to use different user input devices starting from OEM CAN bus selectors, analog selectors, paddle and sequential shifters finishing on analog mode knob or other generic sensors.