At first I thought this meant a userland consisting of common utilities (ls, grep, the usual GNU suspects) written in Go, but that doesn't seem to be the case.
Instead, it seems to be, if you can compile your Go program for AMD64, and it can build without glibc (or any c runtime), then it can be hosted by Gokrazy? Is that right?
My only question is does it work with WiFi? I was under the impression that quite a lot of the Linux WiFi stack was implemented in userland (wpa_supplicant).
The WiFi device itself is handled by the kernel's brcmfmac driver, and there is the usual firmware (also requires a .txt file) or you can use something like nexmon, which tweeks the firmware (and a patched driver to use it) for using monitor mode, injection and a few other misc things people have done with the firmware.