Does anyone know any more about Boox & GPL compliance?

The wiki page effectively says they are in violation:

https://en.wikipedia.org/wiki/Onyx_Boox#GPL_Compliance

> As of 2022, Onyx International Inc. has declined[20] to release the source code with Linux kernel modifications licensed under the GNU General Public License version 2 in response to a written request by a user. The GPLv2 license states that if a modified version of a covered work (such as the Linux kernel) is released, the corresponding source code must also be released under GPLv2.[21]