CAN is a protocol, but the messages on the bus are implementation specific. Yes, you can use it on any CAN bus, but there's no guarantee that you will be able to decode the traffic. Some modern CAN networks are encrypted, too, because it's trivial to view the traffic. https://kentindell.github.io/2021/01/02/can2-wireshark/ has a great guide on decoding traffic with sigrok.
The similarities are pretty strong as is. The method of images https://en.wikipedia.org/wiki/Method_of_images is used in both electrodynamics and aerodynamics because you can model sources and sinks for E fields and fluid flows using the exact same equations. Personally, EM didn't really click until I saw the vector calculus of EM applied to fluids.
No, but that's the point. It has all of the good parts of a smart phone, none of the bad ones. Do other dumb phones run Signal or Maps?