The dashboard is one client of the Screenly API, with no special access. Anything you can do by clicking, you can do from a script.
Each tool below has its own documentation. They share one thing: an API token, which scopes every one of them to exactly your permissions in one workspace.
Web pages sits outside that list, because it is a topic rather than a tool: the fields on a web content item that only a script can reach, JavaScript injection among them.
The full reference, endpoint by endpoint and command by command, lives at developer.screenly.io.