Will you be using city water or your tank? How much of a run from th water heater to the kitchen sink. It takes a little while to get water up to temp, city water not as much issue as tank. For me, it didn’t work because 20 some gal tank and using a gallon to get hot, was not feasible. Plus I lost the 6 gal in the tank of the water heater.
Many have gone this way, but be sure to check the specs on the unit, and how quickly it will heat.