The real world case I remember also included a TODO to return and fix the code later. In a published scientific software. I wonder how many paper were messed up by this buggy software. As I looked at the code due to the amount of bugs I encountered.

It’s been many years from publication, and to the surprise of no one, they did not return to fix it.

// This line does nothing, however removing it causes production to crash. DO NOT REMOVE

You can easily load PDFs into kobo readers, at-least into mine. However, most PDFs will be unreadable. To reads PDFs properly on a e-reader you need a screen that is at-least as big as their render size. Meaning, that if the PDF was built for A4, your experience will be, in most cases, lacking on any screen smaller than A4.

I have no experience using such big eink and can’t comment on their quality.

Bought a math book from them, they refunded it with no questions, after I read a lot of it, because some of the equations were unreadable.