To lower current draw, one could use i.e. an AVR and a UART radio bridge (Bluetooth or similar). Then, the battery could be a lot smaller and the device would

To lower current draw, one could use i.e. an AVR and a UART radio bridge (Bluetooth or similar). Then, the battery could be a lot smaller and the device would be sleeping most of the time. That's possible since e-ink only draws power when updating.