Hm.. I just tried on my Google pixel 7 Pro (obviously very different display - OLED) - and certainly seems like the result of a test conversion pdf2djvu should be at home on an eink screen. Not sure if there's a simple way to test on the only eink I have to hand; a Remarkable.

Fwiw google Gemini cane up with the following to convert pdfs on device in termux after some prodding (koreader can display DjVu):

You'll need access to storage:

termux-setup-storage

Then pipe/paste this to a script: (Sorry for the verbose slop)

Ed: moved to sibling comment