> Did you (rightfully) want to tear your eyes out when some LLM suggested that you script with .mjs?

I respectfully disagree with this sentiment. JS is a fantastic Python replacement for scripts. Node.js has added all kinds of utility functions that help you write scripts without needing external dependencies. Bun, Deno, and Node.js can execute TS files (if you want to bring types into the mix). All 3 runtimes are sufficiently performant. If you do end up needing external dependencies, they're only a package.json away. I write all my scripts in JS files these days.