I would like a source (1) low power, E-ink book readers with (2) an SD card slot that can handle large cards, and ideally (3) open to hacking.
This is a very small set, possibly zero. All of the android readers are ruled out because it's power overkill just to get bits off a card to flip an e-ink screen and then go back to zero power for days or weeks. There used to be some readers with SD slots but those are often limited to 32 gig. And I want (3) in case the reader doesn't handle the formats I want.
Such a machine /would/ be an offline, after civilization goes away machine. You'd want wikipedia, emergency medical handbook, plant identification books, etc etc.