I am excited by the idea of using TOML.
Appearently this has been around for quite some time, but has never really taken off.
There is a thread that is also showing an interesting way, how Idris does source TOML files, but there has never been any further comment on it.
I think TOML is far more readable, and could particulary draw in people from Rust, Python and other communities, where it is popular, or even the default choice.
It could remove the long standing issue, of people being scared of Nix as a language.