Add frequency sensor for Shelly Plus/Pro xPM devices (#97172)

homeassistant/components/shelly/sensor.py

@@ -661,6 +661,16 @@ RPC_SENSORS: Final = {
         state_class=SensorStateClass.TOTAL_INCREASING,
         entity_registry_enabled_default=False,
     ),
+    "freq": RpcSensorDescription(
+        key="switch",
+        sub_key="freq",
+        name="Frequency",
+        native_unit_of_measurement=UnitOfFrequency.HERTZ,
+        suggested_display_precision=0,
+        device_class=SensorDeviceClass.FREQUENCY,
+        state_class=SensorStateClass.MEASUREMENT,
+        entity_registry_enabled_default=False,
+    ),
     "freq_pm1": RpcSensorDescription(
         key="pm1",
         sub_key="freq",