My SatNav used to work like this (sort of).
Plan your journey and points of interest on Google and send the points to the SatNav. Then you just join it together on the satnav. It has a built in phone chip so remained in the car.
Then it all started to fall apart : on board search changed from Google to Here, petrol prices withdrawn, Send to GPS removed on Google maps. It still has some features I like, checks for parking, has a tracker system (I can send an invite to someone and they can see why I am late).
I don't have a smart phone nor want one but the newer units don't have much of this unless you pair with a smart phone.
If TomTom have now started to provide some of this it may get my custom next.