I need to let user access documents stored on my account(app is registered on it) Drive. I know how to access user Drive data with Picker API, but is it possible to access Application data using Picker API?
The point is - I have website, and I want to embed documents from Drive to my App, so users can collaborate on it. I store those on my Drive, and want users to have possibility select those docs, using Picker API(which will return Document.EMBEDDABLE_URL, that I latter embed in <iframe>to view and edit).
Not at all. 'Application Data' is designed for things such as settings and configuration data that an app has per user, but a user should not see. If you wanted to do something like this you'd need to write your own Picker dialog and make sure the correct permissions are granted.