It's all simple in theory, but putting together a build environment is the finicky part. Linuxdeployqt and the various AppImage creation tools are only "supported" on the oldest supported LTS (which is 14.04 on Ubuntu for 1 more year, and probably CentOS 6). But the latest QtWebEngine needs a minimum of gcc 5 to be able to build (14.04 comes with gcc 4.8). So if we want any kind of widespread compatibilty, we're probably looking at Ubuntu 16.04 as the very oldest supported systems. Then it's figuring out what the newest versions of Qt5/Python we can build with the stock libc we're stuck with on our chosen environment.
None of these things are impossible, by any means, but they are very tedious. The easiest part is building the AppDir and then turning linuxdeployqt loose on it. Getting a VM/Container/CI ready that will let us support anything earlier than 18.04 is the hard part.
