If you want this to be powered by a coincell battery or any battery you need to figure out a power budget and pick a wireless protocol. WiFi is incredibly power hungry and won’t happen with a battery unless you like charging it every few days. If you are willing to make it a powered setup it will open many options otherwise youre stuck with zwave, ZigBee, BLE and LoRA. If you want to mix this project with other fun stuff like LoRa/meshtastic look into these. They snap into a main board and you can add a temp and humidity sensor and collect the data over BLE, add a screen and communicate over LoRa for miles. I can get these to run on a 18650 battery for about 3 weeks.