Actually, EinkBro's Reader mode is using Mozilla's readability.js. I've actually been using EinkBro for over four years. One of the main reasons I want to develop Eink Mode is to achieve true pagination, where text and images aren't cut off at the edge of the screen. EinkBro's approach involves scrolling a fixed distance by tapping page turn zones on the screen (just like pressing the space bar when using a desktop) , and it removes the scrolling animation using "jumping" by a 'scrollHeight' amount. However, this still has the issue of potential content cutoff.

Eink Mode + Ebook Mode = A fully functional web browser for Kindles, which is the most popular eInk device by a large margin.

If you combine these two projects, then you will have a great eInk experience for any kind of eInk device, and not much need for a browser plugin.