Comment by squarefoot

Cameras could be built using a single board computer (like the Raspberry Pi Zero, but there are better and cheaper options) plus a USB camera module, and the necessary firmware that could well be just a simple script invoking ffmpeg or similar streaming software; all Open Source.

For example:

https://www.friendlyelec.com/index.php?route=product/product...

https://www.friendlyelec.com/index.php?route=product/product...

https://www.armbian.com/nanopi-duo-2/

Then all video can be collected by applications like Shinobi, Zoneminder, Frigate, etc.

https://zoneminder.com/

https://moeiscool.github.io/Shinobi/

https://frigate.video/

The hardest part would probably be making an enclosure that is solid enough to withstand being exposed to sun, rain, temperature deltas etc. and remain sealed to protect the electronics.