"The majority of the Android platform and documentation is licensed under the Apache 2.0 license. While the project strives to adhere to the preferred license, there may be exceptions, such as for documentation (code comments) extracted from a source code module that is licensed under GPLv2 or other license. "
stated in the android license page
https://source.android.com/license#:...ther%20license.
All code under the GPL must be released. They have not done that. This same thing happen with onyx check the link below.
https://www.reddit.com/r/Onyx_Boox/c...etter_company/
All other companies like remarkable, kindle and the most popular custom ROMS also do it. Check out the reddit thread. Then why not pocketbook?