Whoa! This is a revelation. I already loved Nix and used nix-shell extensively, but this is the missing piece: fully reproducible Python scripts without compromise.

Or install direnv and put your dependencies into a shell.nix, setup the bash hook according the manual, create the .envrc with the content "use nix". Then type "direnv allow".

Then you can do e.g. use other persons python scripts without modifying their shebang.