This isn’t about connecting a temperature sensor in your Arduino. ... The temp sensor 3 pin devices are simple and cheap but good for 0.5 deg C precision or nearly a full degree in human measure.

And yeah, otherwise agree, an Arduino or ESP8266/ESP32 is the better way to go. With an ESP could possibly even go ESPhome, give you a nice WiFi page showing the relay control, both temp sensors ...

If you’ve ever put your finger on an ESP8266 module when it’s really working, you’ll know what went wrong here: the ESP8266 heated up the board and gave a high reading on the temperature sensor.