Cheapo WiFi sensor: How does it work?

[NivagSwerdna]

So I bought a cheap PIR Wifi sensor...  Marked... DP-WP001 V1.3  LH. Chen.

and obviously took it apart (since I don't really want a gadget of unknown provenance on my network)...
I am quite intrigued as to how it works...
There is a PIR sensor and a SGM8139YS16 which is a PIR AFE)...  there is also a 8L051F3P6 which I think is a STM8L051F3 i.e. a reasonable 8bit uP with 8k flash etc... and finally there is a TYWE35S which is an ESP8266 (32bits and 1M byte flash etc).
The TYWE35S clearly has RX/TX connections so I snopped those and got...

Would the protocol between the TYWE35S and the STM8L051F3 be a standard of some kind or is this likely to be totally proprietary?

Could that be the TUYA protocol?

PS
It's a DP-WP001 v1.3

[NivagSwerdna]

FWIW I found 3V3 continuously applied to the PIR AFE so I think it is permanently active.  Must use a wake on change type arrangement for the STM8 and then use the ESP8266 for communication with TUYA between the two.

Quite interesting.... anyway flashing with Tasmota now