Yes and no. So on one hand you'd have to trust the vendor to allow you to control the connectivity (this is likely going to be the same model as iOS and watchOS

Yes and no. So on one hand you'd have to trust the vendor to allow you to control the connectivity (this is likely going to be the same model as iOS and watchOS devices -- unless you add a subscription it doesn't connect). On the other hand, you'd have to trust the vendor anyway, unless you diffuse and package your own silicon and write your own bring-up code and bootloader and OS, there are a rather lage amount of manufacturers you have to at least trust a little bit to get a functional experience. I think the big difference here is that with a Car, you're primarily buying a device for driving yourself from one place to another, and everything else is extra. With a computer, you buy a device to compute, and with that is practically always some internet-connected requirement. Buying a Car without internet, or radio, or infotainment is fine (if you can find one) because the primary reason you want the thing is still intact. A computer without computing and without internet isn't very useful.