Continuing the discussion from NotesCmdr - Slash commands and markdown for Apple Notes:
@rexec mentions in the original thread that he’s overcoming the lack of an official Notes API or SDK by using the Accessibility APIs from macOS. This is quite the workaround!
I also noticed that Tabby uses accessibility API to work as kind of a browser tab & window manager that works across browsers (it supports Safari and Chrome).
So it seems that the Accessibility APIs can act as a uber hack to build features that are not trivial.
Do the MPU hive mind have other apps in mind that work like this I guess Keyboard Maestro and Better Touch Tool are obviously doing a lot of their magic through Accessibility stuff.