You're taking a few F/OSS components (in this case the Linux kernel, the golang toolchain and some custom software) and you're assemblying them into a bootable system.
That's almost quite literally the definition of "gnu/linux distribution".
GNU/Linux, or GNU plus Linux as I’ve recently taken to calling it, means combining a GNU userland (GNU libc, GNU coreutils, GNU compiler collection) and the Linux kernel. The Linux kernel itself is not a GNU project. If you want to use a GNU kernel then you need Hurd, hence GNU/Hurd.
When you replace the whole userland with components that are not written by the GNU project, then it no longer is GNU/Linux. As such this is not a GNU/Linux distribution, and neither is Alpine for example since by default it doesn’t use a GNU userland.
Given this is what the README states, how can it be a GNU/Linux distribution?
It doesn’t include a shell or anything like coreutils either (GNU or otherwise).