I wish env -S was more portable. It's a newer feature of the coreutils env implementation and isn't supported elsewhere afaik.
#! /bin/sh
"exec" "/usr/bin/env" "uv" "run" "--quiet" "--script" "$0" "$@"
# /// script
# dependencies = [
# "cowsay",
# ]
# ///
import cowsay
cowsay.cow("Hello, world!")
On systems that can't run uv, like NetBSD and OpenBSD, switch to pipx: #! /bin/sh
"exec" "/usr/bin/env" "pipx" "run" "$0" "$@"
# ...