Thank you for writing to me. You bring up a great point. Yes I have some people who do that. The problem though is that when you need heat in the pool the most like in the early spring and fall you need cooling in the house the least. So it works a bit backwards sometimes. Also it is sometimes hard to regulate unless you have a damper that will dump the cold air outside if it is too cold in the house and the manufacturers are not thrilled with long duct runs. I also hate to waste all that cooling. It common in the summer to see all the pool guys leaning over the heaters trying to cool off. So I would not go in that direction. Once my friend converted a heat pump to heat and cool the house and heat and cool the pool. It was the most complex thing that I ever saw and only he could work on it. There was also a manufacturer in the late 90's and early 2000's that went one step farther and had it heat the domestic hot water. Incredible technology but they went out of business in 02. On my friends job the homeowner abandoned the house a couple of years later, so all that work was a waste. I would just keep things simple these days.
Sometimes we put them in huge building that are very humid and use the heat pump to heat the pool and dehumidify the building. I hope that helps.