At least with my setup I prefer Amcrest over Reolink (based on compatibility and setup and plugins with the software I use). An open source option that just requires cameras, a computer, and a network is Scrypted + Frigate (+optional Google coral). Amcrest plugin in Scrypted to create a rebroadcast point, then capture it in Frigate for a birdseye view and other security features. If you have Google coral frigate can also do AI object detection (it can do it without but slower). Since Scrypted is the rebroadcast point I also have it hooked up to Apple home kit since I have an Apple TV 4K. Pretty happy so far.

Edit: Another comment mentioned https://gitlab.com/Shinobi-Systems/Shinobi which I haven’t explored but am definitely going to also try out now.