Good idea, but I think it might work better if you had an Android device. Siri is not great at definitions and you often have to literally spell things out for her. (if she hears you at all and doesn't start randomly calling your aunt instead of providing a definition)

I've tried this, but I find the screen refresh of e-ink displays very distracting. I also prefer scrolling text when reading vs. flipping virtual pages - which limits me to non e-ink displays.

I just created a Reading Focus mode on my iPhone that automatically limits the number of apps available / notifications visible when I'm reading. We'll see how this works.