MQTT is available via LWIP on STM32 parts that don't have an MMU. I've tried it on the STM32F746 (Cortex-M7) and it works well, although there are other issues

MQTT is available via LWIP on STM32 parts that don't have an MMU. I've tried it on the STM32F746 (Cortex-M7) and it works well, although there are other issues with networking on CubeMX that are open.