I will make a python version of this that can do arg parsing properly tomorrow.

Here is a rough outline from what I had in my notes on turning this into a proper cli utility

sysext install from buitd system destdirs:
  --persistent (default) -> /var
  --tmp/runtime -> /run
  --ignore-version -> make _any metadata (otherwise parse/copy /etc/os-release)
  --make-tarball
  --make-image

$ DESTDIR=foobar make install
$ meson install --destdir foobar
$ sysext_install_thingy foobar --runtime

Alternative it could also operate on a meson/autotools builddir and run meson install for you in a desdtdir it will manage itself

TBD:
* install in xdg_cache and symlink
* symlink permissions and stuff
* schema/desktop-dbs etc

run integration commands
* glib compile schemas
* update icon cache
* update desktop file/icon? cache

Note that I had sketched this out before importctl was a thing and we could probably simplify it a bit now