Hi,
We will bring the external interrupts/ handlers feature to ArduPy in the near future.
Also to answer your second question, you could convert the existing Arduino library to an ArduPy library by following our guide. It is available as a wiki and also as a video.
Finally as per your suggestions, currently the mentioned features such as MQTT, Wi-Fi, and SD card usage are only available to use with Arduino. But we will think about adding these features into ArduPy as well.
Best Regards,
Lakshantha