I’ve documented the protocol for the Resideo/Honeywell gas water heater valves. The work was done based on the WV8840 but also tested on the WV8860. The devices have a communications port on the bottom where you can query current state and enable/disable vacation mode.
It includes an implementation based on ESPHome and the ESP32C3. The example implementation includes in addition to the communications port a water leak sensor, inlet/outlet temperature sensors, and a water flow sensor. The extra bells and whistles are not necessary of course, just the serial connection for the communications port.
An example of data:
