NOTICE!!! Manufacturer has started using unsupported non-ESP8266 chips recently and this device might not be compatible anymore. Check seller descriptions or contact them before buying!
Warning: As of mid-November 2019, units purchased from Amazon.co.uk would not program with tuya-convert. Issue reported on the tuya-convert Github page as issue #394 https://github.com/ct-Open-Source/tuya-convert/issues/394
It appears that Teckin have changed the hardware and the new devices are using an RTL8710 which won’t work with Tasmota.