The app currently logs diagnostic events to ETW in various places. If we add certain flags to those events, the data is eligible to be sent as telemetry. (Whether it actually gets sent is controlled outside of Calculator--for example, there are lots of checks at the system level to ensure privacy settings are honored.)
Currently we set the "eligible for telemetry" flags only in official builds, so no telemetry gets uploaded while the app is in development. We already have this set up for the main TraceLogging provider, but we also need to do this for the AppLifecycle performance logging.