PaperOS: A native Linux E Ink OS running on BOOX hardware

Honestly, Linux is so thoroughly Tivo-ized on these things that it is not really worth the effort. You will be forever locked into the official firmware's kernel, nonfree drivers and firmware blobs. Pretty much the same problem as most Android devices, as mainline Linux support is a pipe dream.

On top of that, this is supporting BOOX, known GPL violators who will never release sources. There are other E-ink vendors out there who aren't totally antagonistic to the community who builds the software they profit from; Supernote and ReMarkable are two of them.