One thing that is different from docker however, is that we generally
want translations/locales in the runtime. But these are pretty large,
so we want to handle them in a smart way. xdg-app has a feature that
allows splitting a runtime into a base and a set of optional
extensions that are mounted in the sandbox only when they are
installed. I use this in the gnome runtime to split out each
locale. Unfortunately Fedora uses a single large locale-archive file
for its locales, so its hard to do that. This needs some research to
figure out how to do properly.