You might have a look at the Tolino reader, it’s not really libre, but is one of the few e-reader that support Readium LPC (it’s definitely better than any competing DRM, but it’s still a DRM).
Also have a look at The Open Book project, it explains how to build an e-reader on your own.
You can also consider to attach an e-ink display to a raspberry with Calibre installed
You might have a look at the Tolino reader, it’s not really libre, but is one of the few e-reader that support Readium LPC (it’s definitely better than any competing DRM, but it’s still a DRM).
Also have a look at The Open Book project, it explains how to build an e-reader on your own.
You can also consider to attach an e-ink display to a raspberry with Calibre installed