Allwinner? "10 years ago".
There are decidedly more effective SOCs for EInk devices - but these are correspondingly more expensive.
KOreader?
I find it useless; it can do far too little and is massively overrated and the book management is not usable in my opinion.
And if I want more information than the simple plot of my books, then I need a functioning offline information system such as Kiwix or AARD2 - the manufacturers do without something like that because their simple customers don't think of it anyway.
Apart from that, it takes up a lot of space (Kiwix Wiki... need about 80 GB)
And if you want to compare texts, then a split screen is ideal.
Linux readers may be usable for simple users, but they are not usable for more.