I already have a Home Assistant server running the plc's in my workshop over TCP modbus and it is working very stable for a 6-7 months. I can share some info if you like.
But i wanted to connect gmt plc's from outside my shop to my server and when i read that they support MQTT i was very happy for a while, guess im back to square one on that.
I also have a semi working micropython build for 396T that supports networking and IO and i am in the process of porting flash memory, but i am not sure if the staff will allow me to share that here. If i am given the blessing of hanifi i will share most of what i know.