Good question @bobkitz! Also a helpful link @apjk, thanks. Here’s the answer:
Not being a crack with MacOS, I know there is a difference between Finder aliases and real symbolic links. With Obsidian (and probably for other compatible purposes too), one should use real symlinks, made in a terminal using
ln -s TARGET LINK_NAME
Unsure if that limitation still exists, but @Licat warned us against crossing filesystem boundaries using symlinks, since the internal file routines in Obsidian might not be able to handle such.
I show a practical example here: MarkDownload - Markdown Web Clipper - #121 by Moonbase59