^This. OP, for your stated uses, a tablet in a mainstream mobile OS is what you need. Real Android, or iOS. Versus an under-powered, overpriced e-ink device that has a clunky, proprietary OS. Unless you are dead set on getting an e-ink device and nothing else will do, I'd go with a modern tablet. And nobody has better tablets (hardware), and touch/tablet-optimized apps, than Apple. I can admit that as an objective reality, even though I strongly prefer the Android OS and devices for other reasons.

BTW, with a quality tablet, you can tweak and adjust the display settings, not to the point of making it e-ink, but definitely to the point of being highly readable and easy on the eyes. I've been able to do this and can read my tablets and phone for hours at a time without eyestrain. Some tablets even have a high resolution grayscale mode that looks excellent for reading--I've loved using this setting on my Nexus 7 (Android). Another side benefit of buying a real tablet is that you'll get more bang for the buck, you can do a lot more with it. If I were you, I'd check out the large Ipad Pro. Spendy, absolutely, but so is the Sony you are considering, if you spend for the higher end e-ink device.