Electrons move in a conductor very slowly. Far, far, below the speed of
light.

So, when you put a voltage or a source of electrons (which have charge and
eminate their own tiny electric field) at one end of a conductor, what
exactly propagates through the conductor, so that the voltage at
the end of the conductor appears (i.e. becomes measurable) in a
time suggesting propagation of the voltage (or charge) at near light speed?