Well yes that’s a Linux specific target so that’s kinda the point.
Technically you could do libcless on a few other platforms which are not actively hostile to it (yet) like freebsd, but that would have no chance of getting to tier 2 if it was even accepted.
All of these are going to mean you can't link any (non-freestanding) C code, load any dylibs, etc. So you will be fairly limited in what sort of applications you can write. Forget most GUI frameworks, even native ones. You won't be able to load GL or Vulkan drivers for example. You are basically stuck with command line or servers.
With glibc that is a pain, I need to build in a container with tthe oldest glibc I want to support, and that still doesn't cover Alpine. And I dont know if a static musl build would even work for that either (if I need to be able to load GUI libraries).