GAPID is an online debugger and a TCP/IP stack needs to be really fast.
As early C++ adopter I always find ironic how people give examples of C++'s code generation performance.
Back in the old days, tying to use C++ would generate exactly the same kind of performance bashing.
Neither of those examples disagree with what I said. Fuschia's usage is the perfect example of agreement - Go specializes in IO (server workloads) and is then being used to do IO. That's a great usage of Go's particular blend of capabilities.
The use of GO in GAPID would be more interesting if it had any meaningful constraints on it, but it doesn't. It's an offline debugger for something that ran on a device with a fraction of the speed.
RenderDoc would be the meatier Vulkan debugger, and it's C++.