Don't forget the most common pedal-controlled electric (and now electronic) appliance, the sewing machine! In that case, the speed control pedal was a natural development from earlier machines powered by treadles and bicycle-like pedals. There's a parallel in flexible-shaft rotary tools (basically high-end Dremels), which also require simultaneous continuous speed control while both hands are occupied with the work being done. The lack of this requirement is probably why the other machines that were pedal-powered prior to electrification--grinders, saws, (dental) drills, and lathes--did not retain pedal controls.

Other "edge-case" pedals:

- various vehicles

- foot-operated computer mice, for accessibility (https://en.wikipedia.org/wiki/Footmouse)

- elsewhere in music: piano, timpani, kick drum, and harp; organs (and rare pianos) with pedal keyboards (in etymological contrast to manual keyboards)