That eInk display is so cool, thanks for sharing. It would definitely suit this sort of project.
I agree that having images would make the project better. The problem would be downloading and decoding images from the iNat API with the limited memory capacity on an Arduino. I think the memory is too low on a Arduino board to decode images from jpeg or png to bmp on the fly. Downloading an image would also take a long time, especially with limited connectivity. There might be some clever ways to get around this, like storing a hundred or so reference bmp images on an SD card and indexing the species name returned from the iNat API call against this database. The image might not match the species exactly, but could give an idea of what kind of organism has been identified.
I love this kind of thing, so i’ll keep toying with some ideas when I have time. Of course if you get around to wiring something up please keep in touch about how you get on!