Here's a video (long, but worth it, in my opinion): https://www.youtube.com/watch?v=KaBj7acHRHk
InkBox OS is a complete operating system replacement I made for Kobo eReader devices. It currently runs on the Glo, Touch and Mini models. It is built around Qt 5.15.2 and namely features ePUB rendering.
Along that, full KoBox/X11 support is integrated, allowing the user to run X apps natively on the device.
InkBox OS is built around a core concept: security. The root filesystem gets verified at each boot via OpenSSL and a public key embedded into the kernel to ensure integrity. Each package has also its signature. If somehow the signature is not valid, the device will refuse to boot or display a warning. If you wish to customize the system, you'll have to recompile the kernel to change the public key to yours and sign the packages back with your associated private key.
You can download the images here for your device: http://pkgs.kobox.fermino.me/bundles/… Follow the instructions on the HowTo file to get it up and running.
Source code is available on GitHub: https://github.com/Kobo-InkBox