@gked, we have received a number of requests from developers for this capability. Most of the requests have been from game developers who want to use the escape key, since that is a common control in PC gaming. This is also a frequent request from users of remote desktop software who want to be able to interact with the remote desktop as if it were local. This is possible using a native application, but not possible through a web experience, which is one of the application categories we are trying to enable here.
Since this is not possible today, there is no specific telemetry that I can reference.