> With the price of SBCs nowadays, you'll probably save some money just buying an ip camera.

The post you replied to very specifically mentioned using an IP camera. Unless you are paying “proper” money per camera, these days most of them are limited out-of-the-box in ways that are intended to drive you to paying a subscription service to have the recordings stored and processed (and presumably used for AI training whether you agree or not) on someone else's server.

The point of this, and other similar projects, is to host that target server yourself to maintain control and privacy. Where it says “such as […] a USB webcam” I assume it is using the same components and libraries that other options do and so will support common IP camera outputs easily too (assuming your camera doesn't protect its feed, or protects it badly, or you can flash it with alternate firmware that doesn't try to lock you in that way), and where it says “such as a spare Linux board …” spare here implies the target audience is people who are likely to have a spare board/box (or resource spare on their home-lab to host an extra container/VM) available so don't need to buy one at current prices.