Great article! Just a little thing I noticed…
You say:

Next we need to add .pub-cache/binto our PATH since we will be installing a global pub package
MacOS/Linux add:

$HOME/.pub-cache/bin

But, if you use the command like you showed (I dropped the ‘packages’ part):

flutter pub global activate webdev

The pub-cache directory containing the bin directory will become:

$FLUTTER_ROOT/.pub-cache/bin

Where $FLUTTER_ROOT is the place you installed the Flutter SDK to, regardless of having the environment variable set or not.
So, the $PATH should include the correct location, possibly something like:

EXPORT PATH="$HOME/lib/flutter/.pub-cache/bin:$PATH"

Just a little something to be aware of.