Hi, MQTT is a lightweight telemetry protocol designed many years ago, that today is being used for Internet of Things connected products.
MQTT cannot be integrated with thinger at this moment. Thinger.io uses a different protocol based on protoson format (also developed for the platform). With this new protocol, we wanted different things, like REST API support both for sensing or actuating, auto API Discovery, bandwidth saving while transmitting data, and other low level features. So, using a protocol or another is just a term of design. You can decide to use MQTT, CoAP, HTTP requests as many IoT platforms use, or the thinger.io protocol. Each one will have their own benefits. As in different protocols, you will have to write code for the Thinger.io protocol, so your device is able to talk with the thinger.io server. Then, using the provided libraries, you will build a firmware for your device.