Thor looks great! I'd be surprised if something similar didn't exist for most languages, but with many of them living in obscurity because discovery is so hard without a well-established name for that class of tool. Some googling for "CLI framework" led me to oclif ("Thor for js"?) and to https://www.nexmo.com/legacy-blog/2020/06/12/comparing-cli-b... , but that can't be everything.

PS: https://github.com/shadawck/awesome-cli-frameworks also lists some for go and rust, getting there! (though most probably not half as complete as Thor, self-documentation should definitely be a first-class citizen!)