That's pretty interesting; I've always wondered about the internals of those things, as I stared at mine while pedaling up some steep grade. I'm also curious about what the electronic derailleurs and shifters run.
They also never seem to fail (unless the batteries are flat).
Fun fact: my non e-bike has lots of batteries.
2 in the shifters 2 in the derailleurs 1 in the front light 1 in the rear light/radar 1 in the computer + phone AirPods (transparency mode!).