Great work! We with Nixpkgs/NixOS have over the past year overhauled cross compilation, culminating recently with a bunch of parallel efforts recently including

Great work! We with Nixpkgs/NixOS have over the past year overhauled cross compilation, culminating recently with a bunch of parallel efforts recently including Windows cross compilation. People have built Nix with cygwin in the past, it would be nice to get it working in MSYS2/mingw-w64 too.