I did a similar thing a few years ago, I deleted reddit, social media, and other time-wasters from my phone, and now I keep a queue of books in an e-reader app. When I have a few idle moments somewhere, my options are to sit and think (sometimes a nice option), or read some book.

I get through about 2 books per month this way. I haven't noticed eye strain issues, but I tend to keep the brightness low and the font size reasonable. If you struggle with eye strain, you might benefit from an e-book phone case (e.g., https://www.inkcase.com/inkcase-for-iphone/) if you don't want to carry a separate device.