Go established itself as a python/ruby/php competitor. Rust is a c/c++ competitor
Imagine one second Kubernetes, Docker or Prometheus those app have nothing to do with PHP / Ruby. It's related to C++ / Java.
Prometheus is the equivalent of what's at Google and it was built in C++. Same for all the DBs outhere in Go: CockroachDB, NATS, etcd ect ... those are C++ applications related.
However you are talking about projects that are not particularly language dependent as long as the runtime is reasonably performant. They could just as well have been implemented in Java. For many Rust would arguably be a better choice but that is not relevant. Go shines here, but Rust is barely emerging in these areas.
Rust is a C++ competitor in areas where C++ has no competition because a GC is a no go. This is also where the most prominent use cases are.
Most of the fields where rust is making headway, it is making headway for precisely the things that Go is not known for - lack of a garbage collector, strict and expressive type system, robust generics, etc.
