I like the idea of that single-file Python script with inline dependency info construct, but it's probably going to be a bummer in terms of editor experience. I doubt the typical LSP servers will be aware of dependencies specified in that way and so won't offer autocompletion etc for those libraries.
The script dependency metadata _is_ standardized[2], so other LSP servers could support a good experience here (at least in theory).
[1] The Ruff Language Server: https://astral.sh/blog/ruff-v0.4.5
[2] Inline script metadata: https://peps.python.org/pep-0723/