There are some combined space heating + water heating heat pump options out there. A few points to watch out for (1) install of an extra hydronic loop for the air handler can be expensive (2) your air handler + heatpump combination will not run as efficiently because of the losses associated with a secondary loop (3) there's a bit of a trick to getting the heat pump properly sized for cold weather + domestic hot water operation (4) if the demand temperatures for domestic hot water and space heating are far apart, the whole system will run at the lowest efficiency dictated by the highest demand temperature.