Eduard Metzger: Because this is conceptually, from the user experience side, a direct "manipulation" of NotePlan notes (aliases to them), it feels like a core feature, not a plugin (or an official plugin?). In effect it is like creating a Finder alias, with the additional bonus that it very specifically opens NotePlan and not whatever app is set as default by the user for opening .md files (I currently run multiple MD editors, and NotePlan is not my default for that :) "Deep Links" are effectively "on-OS hyperlinks" and are very powerful. We do not see them yet very much because most OSs don't make the capability a "first class" UX pattern (the exception having been "tiles" on Windows Phone and maybe Windows itself?). URL Schema allow us to bring this functionality, in this case via a little known mechanism (the ".url" file).
Interesting, I never heard of this macOS feature. Seems to be veeeery old. Possibly a plugin could do that? We need a the “save file…” dialog though, then it could be possible to build a very simple plugin.