Basic Thermostat for bedrooms with no furnace

So I am looking for a thermostat to put in my bedrooms so that I can set a temperature on them and then it will just run a plug on an oil heater in the room. I don’t want to spend tons of money on these.

I am currently using shelly temp displays and virtual thermostats in Home Assistant to get the temp reading from the room and toggle the plugs but would really love to replace these with thermostats so you can read and set the temp so you don’t need to do it in Home Assistant. Would prefer in wall install so it does not stick out and batter powered but not a huge if does not have that as i can 3D print something to mount it in a wall if needed.

So the smart thermostat in the room will just control the plug in the room through HA