perhaps bare in mind the other reason i chose javafx was its also builds the native wrapper.
(of course this can also be done 'manually' but it provides a few things that are useful and not obvious)
the actually packaging on different platforms is not that hard and if we moved to something other than ant, e.g. scons/cmake is often provided as a target.
I dont particularly like javafx, but its a pretty simple solution, to a pretty boring problem
btw: post install tasks, could possibly be undertaken by the app ... unfortunately java is a bit rubbish at this kind of thing, so you'd be pretty limited to kicking off some other process which could elevate permissions to do the task.
I do wonder though if linux (generally, not axoloti specific) will ever be an end-user platform, the difference in distros, wm etc means its always got incompatibilities.