The serial servo controller is not wireless on its own, but can be paired with a serial radio. You would need a micro-controller to read the potentiometer position and generate serial bytes for the radio transmitter on the other side of the system though, which is much more complication than you need to do just manual servo control, especially if you’re just starting out in control electronics.
Most servo-control radio systems have pretty small receivers (like this one for example, and they do get even smaller). The size of the transmitter usually isn’t so much of a concern, I don’t know of any particularly small ones. Do you mind if the controller is something like this?