Can downloaded content work on smart glasses without internet?
Yes, if the application has stored the content and can read it locally. A cached title, thumbnail or preview is not necessarily the complete item. The app must also support opening it without an online step.
Reopen something you have not just viewed
Distinguish an intentional download from a screen left in memory after an online session. Restarting the app and moving to an unread part of the item gives a more useful check. It reveals whether the underlying content is available rather than only the last rendered view.
For a talk, store a short script and confirm that its later sections open while disconnected. For a document, include an attachment or image if it is essential to the task. The download needs to contain what you will actually use, not just enough to produce an attractive preview.