"Bother"? Motivation is interesting. Getting all excited over what language a compiler is coded in, far beyond any actually, independently useful program, is objectively weird.

C got its legs from a whole OS coded in it. The compiler was very incidental. I don't have any programs in Rust on my SSD. I have one Haskell program: pandoc. I have no Java, C#, Scala, Clojure, Kotlin, or Erlang programs. I have one in Dart I don't use anymore.

A substantial, useful program in Zig that would be too much work to re-implement in a mature language would do orders of magnitude more for Zig than a second compiler. Maybe a collection of pipewire modules, or matrix gateways?

Perceptions of velocity by language advocates have very, very little to do with actual velocity in industrial settings. The latter is what matters, but is actual work to measure. Anybody measuring seems not to be publishing.

We’re actually looking to support Zig as an authoring language for user generated content for Third Room - the spatial collaboration platform for Matrix. Not sure this would be a killer app like a Matrix server or gateway or something, but could help a bunch. https://thenewstack.io/third-room-teases-user-generated-cont... has more details.

Doesn't seem like it needs much support, as such, being able to use ".h" files directly.

You would not want anything that must be depended upon coded in it, in case it fizzles like almost all languages do, but that leaves huge scope for valued additions on top.