This looks really cool! Working on multiple projects with different versions before tools like pyenv or nvm existed was a real challenge. As someone working with different programming languages as well, this tool looks like the next logical step.
Plus is supports many more tools than just the language vms
Volta exists but alas, it's only for JavaScript.
But on unix it is also built using python-build. For me, a light python user, there is no difference between using vfox and using pyenv.