The 2nd gen Prius does have an electric resistance heater for the front windshield defroster and one for the front foot vent. They are operated under certain circumstances. The 2nd gen Prius also uses a coolant thermos that holds warm/hot coolant when you switch the car off and dumps it in when you turn it back on. The 3rd gen got rid of the thermos and instead uses an exhaust heat exchanger, so it can scavenge exhaust heat to warm the engine. The 3rd gen doesn't use the A/C in reverse for heating. There is no need to when there is free warm coolant to be had. There was a heat pump on the prototype PHEV Prius, but it was dropped for the production model.
There is no disconnect between having warm coolant and warm air. They're directly connected. If there isn't warm coolant there isn't warm air.
By using the coolant hack it allows me to keep the engine off more often. The Prius uses an electric coolant pump so you can have heat while the engine is off. But, having the engine off doesn't warm things up as much, so things just stay cooler. Its not horrible by any means, but I thought I'd mention it because it is noticeable.