how about using the kinetic energy of the button press?
There exist already wireless buttons to switch on the light, where the energy put in pushing the knob is used to transmit (range +/- 2m last time I checked). There exist scales that use the weight being put o to operate (they do need a push in advance to calibrate zero)
So why not a remote that does this?
mine is the one with the royalties contract in the left pocket