If a selling point is run from "one file", that's quite difficult to do in python. There are things like pyinstaller but you end up shipping the entire interpreter in the bundle.
As I recall, pex doesn't package up the runtime. It essentially packages up your venv, code, and resources and runs them under an installed runtime. It makes use of a relatively unknown bit of python functionality, which is that CPython will try to treat a zip file as a valid python script.
oh wow thanks i didn't know about this. in that case it would be super simple for me to wrap up a FastAPI server with SQLite or even some in-memory database that runs elsewhere, deliver as a single file!
Yeah this kind of thing was common when I worked at Twitter (where AFAIK pex/pants was developed) on an infrastructure team. It's a cool tool that few outside of Twitter seem to be aware of.