I don't know of any third-party projects that are using it, though from talking to users and looking at the download numbers there are quite a few, they're just closed-source. You can look at the dependent downloads[0] to get an idea of whose using the implementations included with rasn.
> How easy is it to use as a codec layer from other programming languages?
It's as easy as using any Rust code from other programming languages. Rasn is completely IO-agnostic, it works entirely using byte slices (`&[u8]`). So all that should be required is writing a C-friendly layer if doing this by hand, or using a language specific binding library like PyO3 to generate more friendly bindings.
