But they are nowhere near the same niche. Go is much much closer to JS than to Rust by design, it just mimics being lower-level.

System level programming almost by definition requires quite a bit of complexity, and you can’t hide it no matter how elegant your abstraction is. Essential complexity is non-reduceable:

I would assert that writing compilers, linkers, hypervisors, unikernels, GPU debuggers, cloud infrastructure, is system level programming.

Well, that's because Go, as per design, is quite limited. Its type system is lacking things Rust has. The languages have (had?) different goals. You can see one past example in generics. How long it took to finally drag the Go developers to implement them, coming to recognize their usefulness, instead of sticking to the rather limiting "No we want the language to be very simple so that everyone can understand and use it." attitude. Rust has been designed with that safety aspect as one of its primary goals and that will incur some cost in being less simple.