mac app from a python script?

[Dan Stromberg]

Hi folks.

I have a Python 3 script (built on top of gi.respository.Gtk) that runs on
Linux and macOS 11.5.  It's at https://stromberg.dnsalias.org/~strombrg/hcm/
if you're curious.

It works the way I want on Linux, but on macOS I seem to have to start it
from the command line, like:
    hcm --gui
...because I don't know how to create a macOS "app" that goes under
/Applications.

I don't really care about having a single executable on macOS, and I don't
really care about creating a .dmg or .pkg file. I'd be perfectly happy just
running "make install" and putting a #!'d script under /Applications with
appropriate metadata - but if it's easier to do a single executable, .dmg
or .pkg, I'd be fine with that.

I've experimented with a few different options for this (months ago),
mostly py2app, but it doesn't appear to like gi.repository.Gtk much.

What's the most straightforward way of installing a Python script under
/Applications on macOS?  I'd -love- to find a way of doing something
analogous to Linux' desktop-file-install - that is, something that isn't
click-happy, but GUI's are acceptable too if they'll get the job done.

Thanks!