Yes. A dedicated eink reader usually goes into full suspend-to-RAM mode, between each page refresh. Also, e-ink displays consume power when they update. It t

Yes. A dedicated eink reader usually goes into full suspend-to-RAM mode, between each page refresh. Also, e-ink displays consume power when they update. It takes a lot of energy to change the state of the pigment cells, and no power when static. So the always updating, graphically busy interface of an Android phone (even if themed for eink) is much more power-demanding to render.