I think it’s in poor taste when a project comes with a shell.nix checked into the source repository.
Zig has no dependency on Nix, nor does it favor NixOS above other distributions, nor does it even favor Linux above other operating systems.
We also don’t list apt-get commands that you would use on Debian to install LLVM, and we don’t have screenshots of how to set up LLVM on Windows. We don’t have vim editor configuration or vscode editor configuration files in the repo. That documentation belongs outside ziglang/zig source repository.
We also don’t put .DS_Store, *.swp or other editor-specific files in .gitignore. That belongs in the user’s global .gitignore. We also don’t ever assume the user will use git, for example in zig init we do not initialize a .gitignore file.
Hopefully this helps paint the picture. There are an infinite number of third party projects that zig can live with or interact with, from the past, present, and future, and picking favorites is completely outside the scope of the project.