Hi,
To see the messages that an MQTT client is subscribing to from the broker, you can use a tool such as MQTT.fx or MQTT Explorer. These tools allow you to connect to the broker as a client and view the messages being published and subscribed to in real-time.
Alternatively, you can use the Azure IoT Hub Device Explorer tool to view the messages being sent to and from your devices. This tool allows you to view the messages being sent to and from your devices, as well as the messages being sent to and from the IoT hub.
It's also possible to use the Azure portal to view the messages being sent to and from your devices. To do this, you can use the "Monitor" feature in the Azure IoT Hub blade to view the messages being sent to and from your devices.
If you want to view the messages being subscribed to by the embedded device directly from the embedded device itself, you can use a MQTT library or client on the device to subscribe to the messages and view them in real-time.