While it's true, that you can't use nix/guix everywhere, but the ideas are orthogonal to where you can write/compile Go code.
Not looking for a debate: Why can't you use it everywhere you could write or compile Go code?
Re:Go Packaging Proposal Process
by tomjakubowski on Friday July 29, 2016 @02:30PM
(#12188872)
Nix barely supports Windows, for one thing. I don't think Go developers would consider installing cygwin just to run a broken version of Nix. And it doesn't officially support any BSDs other than OS X, I think.
There are a host of other reasons that we could happily debate for years (no thanks), but bottom line: you can't use it everywhere you can write/compile Go code.