In MacOS you can save a URL as a file. Then if you launch it in Finder, it will open the vault/note. So you could create links to each of your vaults.
I just dragged an Obsidian url from Firefox onto Finder. I don’t know if there other ways. This is the contents of MyFancyVault.inetloc so you could just make the file in a text editor.
My vault name is “ObsidianNotes”
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>URL</key>
<string>obsidian://open?vault=ObsidianNotes</string>
</dict>
</plist>
EDIT: There does seem to be a bug though… If Obsidian is closed, using the url, my last-opened vault opens. If Obsidian is already open, THEN it opens whatever url I clicked on. Which is also the case if you simply click on a link.
I filed a bug here.