Room thermostat

I have an Ecobee 3 perfectly working in my house. I am planning into installing some keen smart vents but I want to install some thermostat in some rooms where anyone could setup the temperature for that room and my smartthings would control the keen based on this temperature.
The furnace would still be controlled by my Ecobee but that would allow me to adjust each room comfort with its dedicated thermostat.
For example, on summer, I don’t want my basement to be as cold as my master bedroom. I can set my basement thermostat to a warmer temperature and automatically close the vents and save the AC for the other rooms.
The only thing I miss is the actual room thermostat. it would just be a temp sensor with 2 buttons and a simple display to set a temperature and I want to get the actual room temp and user setup temp in smartthings.
Anything to suggest ?
Thank you