The folks over at Home Assistant found that the device uses MQTT-over-TLS, which can be intercepted: Experience integrating Duux products? - #27 by hamido - Third party integrations - Home Assistant Community
Also, Duux devices that use Tuya can be hardware-modified to enable local control using ESPHome (I did that with my Duux Whisper Flex yesterday).
But both solutions aren’t exactly trivial.
