Flatpaks and Snaps are supposed to replace native distro packaging, in order to be distro agnostic (you could run it on any distro), the issue with Snaps is that it depends on Canonical’s mood and it is Ubuntu “native”, whereas Flatpak is way more used elsewhere.

There is AppImages as well, but it used to a lesser extent.

At current pace, I wonder what you could do with a spear and a club from the future

It depends on the specifics of the install script, it could be it called to directly download and install the binaries (no packaging), or it ran a set of validations then download and install a native package (.deb in this case).

Sonarr takes care of it