LILYGO TTGO T-Camera
This is a very small yet featureful PCCC with battery charger, microphone, infra-red detector, OLED display.
While the highly integrated LILYGO TTGO T-Camera is very cool, as of 2023-04-23, it is MORE expensive than the "supermarket" mobile phone below, making it a niche solution.
Low end mobile phones make the best sensors in a lot of cases. Even "supermarket" mobile phones at AU$47 (as of 2023-04-23) has a lot of features like touch display, rechargeable battery, camera, microphone, satellite positioning etc.