Thanks for the wonderfull onstar component, I have an active onstar account, so I can help you with some urls; What kind of information do you need?
When I open the network tab in developer mode, I see a couple of json-entries (get/post).
That addresses I use in Europe - I need information for US region.
BTW - OnStar just kick me off so I don’t use OnStar anymore. I bought GSM / GPS OBD2 interface from China - I will install it later this week. Then I will try to integrate it with HA. It’s cheaper that OnStar (just prepaid internet sim card) and works for every car.
I was called last week by OnStar, they said to me that they are saw strange behavior on my onstar account.
At that moment I was in a hurry because of holiday preparation and disabled the intregration, but I will contact OnStar what the problem with this HA integration is. For now, the integration is disabled
Well it is more than an rpi, but yeah it is not throw away money!
It provides LTE/4G internet connectivity, GPS, accelerometer and the ODB connector/chip as well as the pi. There is also open source software and an api.
But in NZ$ it is a little expensive, and I have two cars!