Can someone ELI5 how this works? I understand it's sending requests to some API on some server, but what I don't get is how the car receives these commands. What does the entire end-to-end network look like?
The same way your typical shitty IoT device works. There’s an internet-connected module that receives messages from the cloud and then emits the equivalent messages onto the CAN bus or some other bus connected to the BCM or whatever you want to control remotely.