zero point energy generators exist in the modern world only in theory. Any you find that have been made are scams. Scientifically, the zero point energy generator is an ideal that cannot yet be reached.

Yes! Absolute zero has minimal kinetic energy.

The kinetic energy of the car becomes zero when the car halts. If it halts on top of a hill, the energy changes to potential energy.

Zero point energy, or the energy of the vaccum, remains speculative. No one is currently using it for anything, and no one knows how to access it, if such a thing indeed will ever be possible.

The nature of dark energy is currently not fully understood. It might be related to zero-point energy... but if it is, the question arises why the density of dark is about 120 orders of magnitude less than the theories of zero-point energy predict. Predicting that the observable Universe has exactly one atom would be more accurate than that.