Some more complex nix features would not be easy to transpile automatically, but many (i don't have stats sorry) packages are very simple declarations which could be ported automatically.
For example, all language-specific libraries imported from rust/python/etc could very easily be automatically ported, and in my experience, writing declarations for those many dependencies is what takes most time in making a small package (although admittedly i only tried once).
Some more complex nix features would not be easy to transpile automatically, but many (i don't have stats sorry) packages are very simple declarations which could be ported automatically.
For example, all language-specific libraries imported from rust/python/etc could very easily be automatically ported, and in my experience, writing declarations for those many dependencies is what takes most time in making a small package (although admittedly i only tried once).