Describe the bug
The install script fails on the Apple DTK (Developer Transition Kit). This is on macOS 11 Beta 8.

This isn't an issue due to Big Sur, as that has already been fixed (#3853).

Steps To Reproduce

1. Open Terminal.app
2. Paste curl -L https://nixos.org/nix/install | sh
3. See error

Expected behavior
I expected the install to begin on my DTK. Alternately, I would have expected at least an informative message explaining that "We don't yet support Nix on macOS using the ARM architecture...", etc.

nix-env --version output
zsh: command not found: nix-env