Right and also there's a full linux under there with numerous processes running, waiting for touch and other i/o events, updating the display and RAM. Not great

Right and also there's a full linux under there with numerous processes running, waiting for touch and other i/o events, updating the display and RAM. Not great if you want weeks long battery. I would like to imagine an e-ink operating system like what Kindle has: a hardware off by default mode, unless a physical button press is given. It wakes instantly, does its job, as complicated as needed, and then goes right back to hard off until the next wake.