If this was true then Python would already have been rewritten to be GIL-free, and the entire ecosystem of Python packages would have been rewritten to respect its API.

Absence of evidence is not evidence of absence! We're on this thread because Cisco is sponsoring piles of tokens at the problem. No such megacorp sponsor exists for this problem for Python. The megacorps have decided not to sponsor that specific problem.

In my experience it's been much simpler to rewrite programs from Python to <insert lower level language of choice here>