Quill OS is a libre software replacement for Kobo eReaders and is currently looking for wizards.
Quill OS is a libre software replacement for Kobo eReaders and is currently looking for wizards.

GitHub - Quill-OS/quill: An open-source, Qt-based eBook reader for Kobos (and other devices).

Edit: Support for Kobo devices, other brands with the same hardware might work as well.