HOW TO CONTROL LED WITH PUBLISH/SUBSCRIBE MQTT IOT 

Thanks for letting me know. In this case you can try to install an mqtt app on your smartphone. One of the app that I have used for the same is "MyMQT"

Everything has its own benefits and disadvantages so we can't say which one is better because every protocol is better at something. But I have a link for you to have the comparison between MQTT and firebase. stackshare.io/stackups/firebase-cloud-messaging-vs-mqtt

I have recently made videos on esp32 and MQTT. You can check it on our channel.

Did you add this extension on Google Chrome?

You can use mqttx desktop app for the same.

Then you can try the mobile app with the name MyMqtt