As systemd service vs. modern python venv deployment?

[Matthias84]

Hi ther,e, I'm pretty happy by invoking mqttwarn manually 😄

But I tried to transform it to a working systemd service, based upon mqttwarn.service unit example. Unfortunatly modern Debian based OS omit the unmanaged use of pip and encourage you to make use of a virtualenv isolation. Unfortunatly this isn't covered by the .service example file and I strugle to invoke the python interpreter from this venv with the correct mqttwarn source?

P.S. Where are this example files are stored if you just pip install mqttwarn in a venv?