Earlier quoted context omitted.
Meanwhile my SO really enjoys starting the car's climate control when she's about to leave her friend, the restaurant or similar, way out of Bluetooth range. Especially during the winter when it's -15C or below it's really nice to step into a warm car compared to an ice cold car.
Fortunately there is 30 year old tech that does exactly this without any modern app-tier enshittification. You can start a car from 2km away by pushing a button on the key ring. This is a solved problem. That doesn't involve a smartphone.
Besides an app allows much more than a simple on off.
Not saying you should have to sell your privacy for ut, but there are some potential positive things by having the car connected to the cloud. So if there's a way to do that without the shenanigans then that might be good.