Not correct voltage, (your phone expects to be charged at between 5 and 20V or so) the other thing is that by rubbing your feet you gather some electrons, it’s only because you did a lot of rubbing that all the extra electrons (or missing electrons, conversely) pile up or a matter of a few seconds or more, but it immediately discharges in a matter of nanoseconds (1-100 nanoseconds according to this source).
the relevant excerpt
From this stack exchange source: a nasty shock is about 3.7mJ, so for the duration of the shock (100ns) it is 37 000W, but since it took a few seconds at the very least, the average rate at which you collected that electrostatic energy from the carpet is 0.00074W, if my math is correct.
So if you had 1350 friends holding your phone rubbing your carpet, or socks that made your feet 1350 as big, and a very fancy voltage regulator, you might be able to charge a phone at rates similar to a charger?
A hand-cranked or pedal-operated generator, a solar panel would be far more feasible.
