An ETC system consists of three components: a gas pedal (TPS), a throttle valve that is opened and closed by the electronic throttle body (ETB), and an engine control unit (ECU).
The ECU runs software to determine the required throttle position from data coming from the TPS on your gas pedal, engine speed sensors, and cruise control switches (if applicable). The electric motor is then used to open the throttle valve to the desired angle via a closed-loop control within the ECU.
Pedal Commander is very simple, it speeds up the signal sent from the TPS to the ETB, which is then sent to the ECU to determine how much to open the throttle valve (dependent on which mode you're in). BUT this is only in effect when the TPS is being actively used AKA when pressure is being applied to the gas pedal. If the pedal is stationary at 0% (such as when you’re coasting, applying the brakes, using cruise control, etc) the Pedal Commander has absolutely no effect on anything to your vehicle.
Failsafes: All vehicles with TPS have a 'limp-mode'. If something within the electronics fails, (say the TPS and the ECU are not talking to each other in a way that they can understand) the ECU shuts down the signal to the TPS and a set of springs in the throttle set it to a fast idle, fast enough to get the transmission in gear but not so fast that driving may be dangerous.
This is active in ALL vehicles, with or without Pedal Commander. If it becomes unplugged, you go into limp mode. If the sensor gets fried, you go into limp mode. If the electronic throttle body is unplugged, you go into limp mode. If the ECU is unplugged, you go into limp mode.
It is no more dangerous than running out of gas.
As promised, I've attached our current CE certification for Pedal Commander. The product has been tested and is completely safe for use. It's in Turkish, as that is where the product is manufactured.