Thanks for your support! Sync is end-to-end encrypted so the server doesn't know about specific paths in your vault. You would have to set those permissions at the filesystem level, or with the tool you're using.
I'm not sure how to make it work but like others in this thread I have an interest in sharing some - but not all - of my notes with some AI agents. Would love a solution that is built in to Obsidian / Obsidian Sync.