I'm aware of java being used for embedded, but that wasn't really proper java and it requires specialized hardware. You can't just expect to run java on an arm microcontroller and expect it to work out. I'm curious to learn more about production quality golang kernels. I've never heard about this before. Personally, if a language doesn't give you the flexibility required to run it on microcontroller grade hardware, I find it difficult to ascribe it systems programming language status. Anything with a large runtime makes that difficult without some sort of hardware assistance to offload the runtime (eg javacard).