One-line installation fails on macOS Mojave: 'realpath: command not found'

Overview

When attempting the one-line installation on macOS Mojave, it fails with an error about realpath not being found.

Here's the Terminal output:

$ curl "https://gitlab.com/gitlab-org/gitlab-development-kit/-/raw/main/support/install" | bash
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2203    0  2203    0     0   9157      0 --:--:-- --:--:-- --:--:--  9179

INFO: This is the GDK one line installation. For more information, please visit:
INFO: https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/index.md#one-line-installation
INFO:
INFO: The source for the installation script can be viewed at:
INFO: https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/support/install

Cloning into 'gitlab-development-kit'...
remote: Enumerating objects: 24213, done.
remote: Counting objects: 100% (7611/7611), done.
remote: Compressing objects: 100% (1081/1081), done.
remote: Total 24213 (delta 7409), reused 6554 (delta 6530), pack-reused 16602
Receiving objects: 100% (24213/24213), 21.67 MiB | 10.41 MiB/s, done.
Resolving deltas: 100% (16550/16550), done.
support/bootstrap-common.sh: line 3: realpath: command not found
make: *** [bootstrap] Error 127

If you are a Homebrew user, you can brew install coreutils and this gets you past the error. (Props to https://github.com/whatwg/html-build/issues/90)

Proposal

I can think of at a couple of ways to fix this, not sure which is best:

Document this in the dependency installation instructions section.
Alternately, a 'realpath' function could be created "inline" in the bash script instead. See https://stackoverflow.com/questions/3572030/bash-script-absolute-path-with-os-x (also mentioned in that issue)

Environment

Operating system: macOS Mojave, 10.14.6 (18G9216)