I am also curious about this, I think Go is a good middle term between Python and Rust, considering that the language is compiled and has a type system (that it is not amazing by any means, but still better than not having one), but is also more accessible than Rust and have a better standard library (though also quirk, flag for example is awful for any serious CLI tool).
If Go was a language that was more used I would probably have started nixos-rebuild-ng in Go instead of Python to have lower startup times (since I think this is an important metric for a CLI tool), though I am quite happy with the startup times right now.