Large scale e-ink always seemed like a good medium for digital signage because it works in bright light.

A friend's wife works at the United Nations, and a couple years ago I got invited to have a drink at their bar, I was really looking forward to seeing the e-ink wall display (made of tiles of smaller screens - not an entire surface) but unfortunately it was broken so I never got to see what it was like in person :( https://www.youtube.com/watch?v=pnb4tFK4I90