It makes sense to still have a main function. It doesn't make sense to have a class only to wrap that main function.

What? When did that go away? What is the alternative?

In a pyproject.toml file you can create/define scripts that reference an entry function. E.g.:

    # myapp/app.py
    def main():
        print('Hello!')

and in the pyproject.toml:

    [project.scripts]
    app = "myapp.app:main"

You can still use the __name__ check at the end of the file, e.g.:

    if __name__ == '__main__':
        main()

That way it works both as a standalone and when installed via pip/uv. -- Note: The scripts created by the installer are slightly more complicated versions of that __name__ check that handle the application argument (arg 0) and the exit code as the return value from main().