There's been a no-GIL Python for about a decade, and it's still OSS on BitBucket somewhere with a PSF license (I used it for quite a while), but at the time, the community didn't want to wrestle with some of the issues, like, do you want to forego atomicity for list appends, or do you want to slow them down (Skython took the former route)?
https://lwn.net/Articles/640177/