Hey'all! We're BlueBuild, a FOSS community project focused on making the customization of image-based atomic Linux distributions a breeze. (atomic @fedora, @UniversalBlue
If you haven't heard about torcx, don't worry about it. It's a rather specific tool for a very limited use case. Sysexts on the other hand make customising immutable, image-based Linux distros like Flatcar a lot more flexible!