Anything you use to sync text files can work to sync an Obsidian vault. You don't need a database.
The simplest thing for a HN audience is probably "put your vault in a git repo and push to github whenever you want to sync," though that isn't real-time.
The simplest thing for a HN audience is probably "put your vault in a git repo and push to github whenever you want to sync," though that isn't real-time.