Researcher has developed, at a cost of less than one dollar, a wireless light switch that runs without batteries, can be installed anywhere on a wall and could reduce the cost of wiring a house by …::A U of A engineering researcher has developed a wireless light switch that could reduce the cost of wiring a house by as much as 50 per cent.
Back in 1956, the Zenith TV remotes didn’t require a battery and just used the power generated by pushing the button. They were severely limited in the number of buttons available though, due to the technology of the time.
https://www.theverge.com/23810061/zenith-space-command-remote-control-button-of-the-month
Those worked by sound. No power was needed or generated by the remote.
From the article…
I THINK I even remember, way back, random channel changes from tapping on a drinking glass or something similar… Cool tech for the time