The popular case-maker Spigen is collaborating with Ossia, a true-wireless charging pioneer, to bring a phone case that integrates the necessary Cota technology to market. The two groups have brought renders of this product (which comprises a 'phone sleeve' and a transceiver) to this year's Mobile World Congress (MWC19).
https://www.notebookcheck.net/Truly-wireless-charging-is-closer-than-ever-thanks-to-a-Spigen-Ossia-partnership.410785.0.html