We had one in Germany, way back in — way back! It also heated the water to wash!
Properly designed, such as by using cool water to condense the water extracted from the dryer,(this provides a “vent-free” dryer), and then using that now warmed water for the next load, could give an astonishing efficiency.
Decades ago, we had water-saver washers that used one load’s rinse water as the wash water for the next.
Have we stopped thinking since then?