LilWeatherPi primarily exists as a backup for temperature, humidity and atmospheric pressure readings.
It also exists as an experiment platform for random rabbit chasing.
There is a pretty decent writeup on www.drgerg.com here. The most recent article is here.
WeatherPi and LilWeatherPi both have the secondary purpose of providing video from outdoors. They inform me about the weather and they keep an eye on parts of my property that would otherwise be missed by the other cameras around the place.
LilWeatherPi runs on a Raspberry Pi Zero W. In the same water-tight box lives two 18650 LiPo cells, a charger, the Arducam, an Adafruit DS3231 RTC, an ADS1115 ADC, a BME280, a DHT22, and a PWM controllable fan. It's a lot of stuff.
The box I used is a Cantex 5133705 4x4x2 PVC junction box. The only reason I put that here is that the 3D printed parts in this repository are made to fit that box.