i have bad news: bash is already a massively improved/extended ksh clone. ksh was a massively improved/extended sh clone. sh got a ton of improvements early on.
this is about as good as you can get without breaking compatibility completely (bash already breaks compatibility with posix sh in some ways).
anyway, once you’ve figured out the hermetic incantations required to work with filenames with whitespace in them, it’ll be time to write scripts that can handle filenames with newlines in them :D
it took less than a day for someone to break run0 totally open, so basically, you have a choice between a well tested/debugged sudo and this new thing which may eventually mature