emacsPgtkGcc install failing on MacOS Big Sur with home-manager

[ParetoOptimalDev]

I have an error installing emacsPgtkGcc on Mac OS Big Sur. I searched the issues and found #33.

Likely issue is that this mac I haven't used in a while has an outdated nix version and outdated nixpkgs (but that shouldn't matter if the expression pins it?), so I need to update nixpkgs without emacs/gcc first, then retry again. I'm waiting for the build of emacsPgtkGcc to finish which will also update nixpkgs to verify this. If this is the case, hopefully this issue will be useful documentation if anyone in the future finds themselves here.

I was wary of mixing up nixpkgs and home-manager channels, so here those are along with the emacs-overlay input:

nixpkgs
  owner: NixOS
  branch: nixpkgs-unstable
  repo: nixpkgs
  rev: 30d3d79b7d3607d56546dd2a6b49e156ba0ec634
  
home-manager
  owner: rycee
  branch: master
  repo: home-manager
  rev: e39a9d0103e3b2e42059c986a8c633824b96c193

emacs-overlay
  owner: nix-community
  branch: master
  repo: emacs-overlay
  rev: 443a8d4881752222d9e1eed515e5f259c6785b6e

I try to install using:

emacs.enable = true;
emacs.package = pkgs.emacsPgtkGcc;

But get the erro:

checking for gcc_jit_context_acquire in -lgccjit... yes
checking for libgccjit.h... yes
configure: error: The installed libgccjit failed to compile and run a test program using
the libgccjit library; see config.log for the details of the failure.
The test program can be found here:
<https://gcc.gnu.org/onlinedocs/jit/intro/tutorial01.html>.
You can try compiling it yourself to investigate the issues.
Please report the issue to your distribution if libgccjit was installed
through that.
You can find the instructions on how to compile and install libgccjit from
source on this site:
<https://gcc.gnu.org/wiki/JIT>.
builder for '/nix/store/jg1xkiw6f5d6py3xmwsxyp08br7y08kz-emacs-pgtkgcc-20220412.0.drv' failed with exit code 1
cannot build derivation '/nix/store/jkzaw0b7why8dzlzw4ga4hxx317hsjgi-emacs-pgtkgcc-with-packages-20220412.0.drv': 1 dependencies couldn't be built
cannot build derivation '/nix/store/qjzxff8xhcj1hpckib7xfkb36xnlhh7p-home-manager-fonts.drv': 1 dependencies couldn't be built
cannot build derivation '/nix/store/wdd0msrzc73lk84z9fs8h9ba2r0syzzw-home-manager-path.drv': 1 dependencies couldn't be built
cannot build derivation '/nix/store/ck9nia8570566p6djgm190fc1mclpnj1-home-manager-generation.drv': 1 dependencies couldn't be built
error: build of '/nix/store/ck9nia8570566p6djgm190fc1mclpnj1-home-manager-generation.drv' failed