I am not a fluids, thermo engineer, but maybe: Use a heat pump to boil the water with efficient transferred heat (instead of higher energy generated heat), and

I am not a fluids, thermo engineer, but maybe: Use a heat pump to boil the water with efficient transferred heat (instead of higher energy generated heat), and some kind of heat recapture from the steam. The heat used to boil the water could largely be extracted from the steam, to increase efficiency, and speed up condensation. If this could be done with a small unit, it would be a nice upgrade over the common end-point on-demand hot water heater. Any temperature water from just under boiling hot, through regular "cold"/room, down to chilled, based on heat recapture level. Always clean.