Hello,
I have made a library so that an AppImage can update itself. It is a Qt library and presupposes Qt as a development environment.
I use it myself in several of my programs and it has worked fine so far.
Interesting to get views!
I have made a small film and there is a small test AppImage you can try yourself.
Tools and programs that I use.
appimagetool
linuxdeployqt
zsync
makezsync
Greetings
Ingemar Ceicer