I don't read fiction outside, I visualize heavily & wouldn't immerse in either the outdoors OR the story if I did
As a birder, I use the phone plus Merlin Bird app which has not just field guide pix but also sound recordings. Or I use physical dead tree books that I can mark up & more easily flip through. Also it's more easy to pass around physical field guides in the field...
I found the Kindle was becoming dead weight on my trips