Organ pedals would work for that. I think typically those just use magnets and reed switches (when connected electronically rather than mechanically). Not to

Organ pedals would work for that. I think typically those just use magnets and reed switches (when connected electronically rather than mechanically). Not to be confused with reed organs, which usually just have one big pedal that operates the bellows. Though sometimes they also have levers you can push to the side with your knee.