The bq cervantes[1] is completely open source. It runs an old (old) Debian Linux, but it's OSS top to bottom, they tell you how to get into it and run your own

The bq cervantes[1] is completely open source. It runs an old (old) Debian Linux, but it's OSS top to bottom, they tell you how to get into it and run your own firmware, their e-reader app is open source, and you're free to hack it apart as you see fit (koreader has a target for it too). [1]: https://www.bq.com/es/cervantes-4 https://www.bq.com/es/cervantes-4