Public apps are identified in the URL by their handle which is typically a dash-separated lower-cased name of the app. Unpublished apps are instead identified by their API key. There is not an endpoint you can query for that value, but the above describes the typical form it takes.
I've seen plenty of examples of both approaches (redirecting to the admin, aadmin/apps, or admin/api_key where even if you're a published app, the api_key should resolve as your handle.
Cheers.
