Thank you for the article, very interesting. In my low power project I also switched away from my usually preferred esp32 in favor of a more battery efficient MCU. I also am not using wifi nor ble but lora instead.
Not OP, but Atmel AVR or TI's MSP430 are good choices if you need low power. The nRF24L01+ from Nordic Semiconductor is a good RF alternative for low power and long distance.