By far the most usage of Go is web backends. But it is true I should have mentioned Java in the language list. Go is a popular Java replacement.
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.
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.