Does Room Sensor work stand-alone?

I don’t need the thermostat, but would love to see the temp & humidity on my phone while I am away. Do these work without the thermostat?

No. The Room Sensor is an Accessory to the Thermostat. Not a stand alone device.

If you have the Wyze Home Monitoring/Wyze Sense Hub you can use the Wyze Climate sensors for temp and humidity.