Hi there~ Unfortunately, we do not have the library to support MQTT with Wio GPS Tracker(2g) so far. Perhaps, you can consider our Wio Lte, https://www.seeedstudio.com/s/wio%20lte.html. The Wio Lte do support MQTT. You can check the library for Wio Lte below.
<LINK_TEXT text=“https://github.com/SeeedJP/WioLTEforArd … client.ino”>https://github.com/SeeedJP/WioLTEforArduino/blob/master/examples/mqtt/mqtt-client/mqtt-client.ino</LINK_TEXT>
https://github.com/knolleary/pubsubclient
Have a nice day.