WIFI+RF Thermostat with mains & Battery backup. Saswell T19WHB-7-RF-WIFI

Has anyone any experience with the Saswell T19WHB-7-RF-WIFI and if you can somehow link it to OpenHAB?

[https://www.saswell.com/7-day-wireless-programmable-thermostat-t19whb-7-rf-wifi_p50.html]

Ive been after a boiler thermostat that:

The thermostat can be placed anywhere in the house and will communicate DIRECTLY back to the boiler On/Off via RF frequency (in case the Wifi goes down, which is why I dont want a pure WiFi product). It needed to be battery operated or battery backed. Needed to be WiFi capable so that I could remote control it and also hopefully pull information into OpenHab.

The Saswell seems to do all of that, plus you can run the thermostat side from both battery and mains.

And it only costs about £45 or about $55, so its cheap!!

Ive found that you can use their phone Application to direct control the thermostat if you DONT give it Wifi access (it creates a WiFi access point for the phone to connect to).

I however cant find any information about what protocols it uses and I cant see anything about Alexa or Google skills… though theres a suggestion Saswell support Opentherm (though this is a speculation on my part, because the pure RF model says it supports Opentherm).

Has anyone come across these? Any idea if these can be communicated with? Any other suggestions that DONT require me to go buy an intermediate RF/Wifi home hub solution.

Thanks