Ditch the keyboard and price it like a kindle and I'm sold.

You may try to import Hisense e-ink phones from china.

They can be flashed with Lineage OS and have a standard smartphone form factor but with an e-ink screen.

Pay attention that they also exists with color eink screen and that those versions are more expensive.

Check out the Mudita Kompakt.*

*not priced like a Kindle :)