I'm currently building this (plus more) - the happy path of what you're talking about is almost complete. There are fundamental issues preventing what you're talking about being used as a complete replacement for NixLang: you'd need every possible language installed/available on the builder machine in order to build packages, and lazy evaluation would completely break (merely evaluating all of nixpkgs takes hours). So you do ultimately need a primary language. That being said, for devops-like stuff there is no reason to have that limitation.
I wanted to use Nickel, but it turns out that it can't do everything you'd need it to do to completely replace NixLang. So right now I'm bikeshedding on what to use instead (and desperately trying not to invent something), in other words it's definitely being renamed. Either way there's a bash script in the `test` dir that shows the general concept.
