Let's Control It

Is there any type of Sonoff device that would have one relay, POW and input to the temperature sensor? I can't find anything like this on Ali or Shopee.
As I understand it, if the ESPEasy firmware is installed, the DTH22 temperature and humidity sensor can be used instead of the original temperature sensor only.

There is none and to be honest, I'm glad there isn't any.
The POW units are directly connected to mains power as they need to measure mains.
So connecting any sensor that's physically accessible outside the enclosure is also connected to mains.
This does require a lot of safety measures to pose no harm to users.
For example the isolation of the sensor must be able to withstand > 300V.

One could isolate the parts so the POW sensor only communicates to the ESP via galvanic isolated components like opto couplers, i-couplers (quite expensive) or those isolators used in ethernet devices.
Also proper care has to be taken to the isolation on the board and to be honest, I don't trust Sonoff to do that as they tend to shave off every 1/100th of a cent on the BOM where possible, without taking quality, safety or parts endurance into consideration.

THX for answer !