Given this is a recently accepted standard (PEP 723), why would language servers not start to support features based on it?
Consider an editor feature, e.g. goto-definition. When working in a normal Python environment (global or virtual) the code of your dependencies actually exists on the filesystem. With one of these scripts with inline dependency information, that dependency code perhaps doesn't exist on the filesystem at all, and possibly won't ever until after the script has been run in its special way (e.g. with a `pipx run` shebang?).