Finally, the reMarkable has the best free software compliance of any hardware device I’ve seen: the settings dialog clearly lists every piece of open source software used, along with its license. Because some of the software is GPLv3 licensed, they also provide root access to the device over SSH. Poking around it appears that it’s running a QT Embedded application on Linux. I’m planning to try some other experiments when I have a moment (can I write a piece of software that uses the e-ink via frame buffer?).