This has been discussed before. See here: Shelly Plus Smoke testing the alarm will not set binary sensor to on.
I use the Shelly Smoke Battery Status as a reliable indicator of the smoke detector communicating with HA.
If the Battery is not “Unavailable” than the smoke detector has transmitted the batter status to HA. Battery = “Unavailable” is a problem (actually, any sensor in an “unavailable” state is a problem).