Slightly related: I’d love to see a cheap DevBoard available which can be programmed easily and runs well on battery. While ESP8266 and ESP32 dev boards can be programmed easily, they use a lot of power due to their added components and not energy saving way of making.

The ESP8266 and ESP32 chips are reasonably energy saving but there are afaik not cheap boards which leveraged the property.

The SparkFun ESP8266 Thing [1] might come close, but is not very cheap.

[1]: https://www.sparkfun.com/products/13231