I was thinking uBeam.[1] Remember uBeam - wireless charging via ultrasonic audio? They've been hyping that since 2011. Was supposed to ship in 2015. CEO replaced last year.[2] Disappointing demo at CES 2019 - they can light up a LED at 1m range.[3]

[1] https://techcrunch.com/2015/04/26/kill-the-cord/

[2] https://techcrunch.com/2018/09/20/ubeam/

[3] https://liesandstartuppr.blogspot.com/2019/01/more-ubeam-at-...