That was my thought / use case too. I'd love the ability to quickly add notes to my existing obsidian if I'm in the terminal. For longer notes, with images, links etc I'd rather use the GUI.
Funnily enough, this WAS the original idea, to have a cli tool that acts as a sort of plugin for Obsidian, to be used when in hurry. I looked for APIs and libraries that could make this possible but couldn't find any.
This will be a great circle back :)