Hi Michael–thanks for getting in touch!
Good question. Any event can be published as a Private event in the Visibility settings in the same way that a default WordPress post can.
Another idea (though it would take a bit of customization) would be to designate a specific category for private events, exclude that category from the main calendar views, then create a new page template that queries those events using the tribe_get_events() function. A little lifting for sure, but definitely an option.
Does this help answer your question? Please let me know. 🙂
Cheers!
Geoff