MQTT is very good for this. I had a hairball of a raspberry pi setup driving a distillation process. I bought a ten pack of NodeMCUs (esp8266 but same basically) and moved all of the hardware off of the pi and distributed it across 4-5 of the little dudes. All comms were MQTT over WiFi and it worked great. (NodeRED was fantastic driving all of that, and i used Tasmota on the NodeMCUs, theres an ESP32 build for that.)
For low power you can obv turn off radio when youre not using it. Probably some simple way to sleep/shut it off completely as well.
BLE should draw less power. Wifi is too power hungry to run on batteries. I first bought two Shelly wifi sensors but then switched to Sonoff Zigbee enabled sensors because the wifi devices only send a couple of samples a day. BLE a better choice but unfortunately most consumer IoT BLE enabled sensors come with proprietary junk and encrypted protocols (Xiaomi, looking at you) most of them are not worth the hassle.
For low power you can obv turn off radio when youre not using it. Probably some simple way to sleep/shut it off completely as well.