Unexpectedly I found an interesting setup.

There's a reader named Xteink X4. From the hardware point of view it's just an ESP32-S3 with a simple e-ink display, and a case with a couple of buttons. Key points here are:

• Price of ~$50 USD on AliExpress
• Vendor doesn't try to lock you in!

You just get a usable hardware for a reasonable price. When you attach it to your PC, kernel just detects the usual /dev/ttyACM0 with the standard ESP32-compatible proto.

And here begins the magic: there's a custom firmware named Crosspoint which does support usual .epub. And it has OPDS support but there's also a ready-to-use Calibre plugin for seamless integration.

Then you just connect your Calibre to your Wallabag which, in turn, has integration with almost everything that used to be Pocket-compatible. For example you can connect it to ttrss for RSS streams or use some mobile apps.

In the end we get a cheap, light, compatible pocket reader for every day carry with more or less automated newsfeed. And yes, if you want to read books there, KOReader Sync Server is supported as well.