Interesting thoughts. Personally I use a pocketbook to read. It’s been pretty good with a red light backlight for the dark(that is gentle for the eyes before sleep) a built-in dictionary and the ability to export notes from books. This is everything I need in an ereader. Unfortunately it has a browser, some unnecessary small games and some other features that anyone who buys relatively expensive ereaders(hence is committed to reading books) won’t possibly ever need.
But the unnecessary features won’t bother you too much. The UI is clean and easy to navigate.
Pocketbook is not open source or anything, but at least I don’t fund Amazon’s monopoly, it’s a smaller company and it’s definitely value for money imo.