I saw Boox called out, but not the Boox Palma². I just got it and it’s been pretty nice. The major draw is the form factor though as it’s phone sized making it pretty portable.

It runs android and I’ve set it up to work with AudioBookshelf and Komga

AudioBookshelf, while designed for audiobooks, allows you to download books for offline reading and seemed the best all in one for books self hosting. It also has a native android app.

Komga seems pretty amazing for manga and comic books (haven’t settled on an app, just using the browser now). The e-ink display isn’t the best for reading this medium, but it’s not terrible for black and white comics.

Since both of those are self-hosted solutions they could integrate with readarr pretty easily (although audiobookshelf’s folder structure can be frustrating).