__init__.py

import sys
import json
from wsgiref.simple_server import make_server


def make_app(handler):
    def app(environ, start_response):
        status = "200 OK"
        headers = [("Content-type", "application/json; charset=utf-8")]
        start_response(status, headers)
        return [json.dumps(handler(environ)).encode("utf-8")]

    return app


def run_app(app, port):
    httpd = make_server("", port, app)
    print(f"Serving on port {port}...", file=sys.stderr)

    # Serve until process is killed
    httpd.serve_forever()

hello.py

def hello(name: str) -> str:
    return f"hello {name}"

main.py

import foo
from foo.hello import hello


def main():
    app = foo.make_app(lambda environ: {"message": hello("world")})
    foo.run_app(app, 8000)


if __name__ == "__main__":
    main()

Makefile

run:
	python -m main.py

build:
	python -m zipapp -c -o app.pyz ../myzipapp -m "main:main"

clean:
	rm -f app.pyz
	find . -name __pycache__ -type d -exec rm -rf {} + 

.PHONY: run build clean