2015 and later variants of the Prius already have this via the solar roof option: https://www.jpauleytoyota.com/blog/how-does-the-toyota-prius...
“If you want to activate the solar powered ventilation system before you get out of the vehicle it is a simple process. On the left side of the steering column, you will find a small square button with a car and fan on it. Press this button before you turn off your vehicle and you are all set. Next time you get in your Toyota Prius it will be nice and cool.”
Edit: apparently it’s limited to running the fan, there’s also a remote a/c option that’ll run for a few minutes off of battery before you get to the car.