put together a small Automator Quick Action that lets you right-click any folder in Finder and open it as an Obsidian vault. If the folder is already a known vault it opens immediately — if it’s new, the script registers it in obsidian.json, restarts Obsidian once to pick up the change, then opens the vault.
No third-party apps needed — just macOS Automator, zsh, and Python 3 (ships with macOS).
Gist with the script and setup instructions: https://gist.github.com/addhass/6a533b940cb12d3b684cfbc238c8d486
I noticed this has come up a few times on the forum (here, here) without a macOS solution, so hopefully this helps someone.