There already is a fork of Emacs for MacOS, which I and others on this site have been using for many years (me since 2010) because this isn't the first time the Emacs project has neglected or outright sabotaged Emacs on MacOS:
One time (roughly 2012) FSF Emacs was in such a bad state that you couldn't interact with it at all: it would display as small, un-resizable window, but nothing I did would cause anything sensible to appear inside the window.
Whether `ls` is the BSD-derived ls that is shipped with MacOS or GNU ls has effects on how well Dired works, and a similar thing applies for M-x grep and M-x compile, but coreutils has no bearing on whether Emacs can successfully draw a window (frame in Emacs terminology) on the screen that is functional enough to, e.g., echo the user's keystrokes.
I know that because I used to have GNU coreutils installed on my Mac, then I was a Linux user for a little while, and now I am back on a different Mac, but I have yet to bother installing GNU coreutils on this Mac and I notice no difference. Also, I've been using Emacs since 1991.
But yes, I am almost sure I had GNU coreutils installed when I had the very pathological problems with FSF Emacs circa 2012.
There already is a fork of Emacs for MacOS, which I and others on this site have been using for many years (me since 2010) because this isn't the first time the Emacs project has neglected or outright sabotaged Emacs on MacOS:
https://github.com/railwaycat/homebrew-emacsmacport
One time (roughly 2012) FSF Emacs was in such a bad state that you couldn't interact with it at all: it would display as small, un-resizable window, but nothing I did would cause anything sensible to appear inside the window.