Wi-Fi is great for quickly connecting devices to a network, but it is a bit power-hungry. It is therefore not the best solution for low-power sensor nodes that must run many years from a single button cell or that live from power harvesting. A great solution for this type of device is MySensors (https://www.mysensors.org/), an open-source home automation and IoT project based on ISM-band radios, notably the nRF24 by Nordic Semiconductor and HopeRF’s RFM69. The more recent nRF5 platform as found on the BBC micro:bit can be used too.

More details at Elektor Labs: https://www.elektormagazine.com/labs/...

The required electronic components can be found in the Elektor Shop: https://www.elektor.com/

Videos cited in this video:
- Home Automation With Home Assistant and ESPHome - First Steps:    • ESPHome and Home Automation With Home...  
- How-To: Integrate You Doorbell in Home Assistant Using ESPHome:    • How-To: Integrate You Doorbell in Hom...