homeassistant

I use Raspberry Pi Zero W's with the cheapest wide-angle USB cameras I can find. PS3 Eyes used to be (pre-covid) ridiculously cheap on eBay (like $6 each if you could find them in the bulk packaging). I dunno if you're gonna find anything that cheap in 2025, but if you can find PS3 eyes on the cheap, they get the job done (but don't work great in low light). Mine (about 8 total) have been running well for about 7 years now, some indoors, some outdoors (mounted strategically to avoid rain and heavy wind).

You can install Raspberry Pi OS (or your lightweight distro of choice) on each Pi and then install the Motion package, which supports pretty much any USB camera out of the box, and lets you set up things like motion detection, image capture, live streaming, etc with a little configuration. If you've got HA running smoothly, I suspect you'll be able to tackle setting up a few Motion configurations. You just SSH into each headless Pi and configure Motion to start in daemon mode so it's always running whenever the Pi boots. You can then access the camera feed remotely from the Pi's IP address with an address like http://<local.ip.address.>:8080

A bit of work to set up (and maybe more expensive than cheap, cloud-based, AIO systems), but it's incredibly worth it to have a wholly cloudless, entirely local security/nannycam solution.

A finished Pi Zero W + camera unit has a pretty small footprint, and can be mounted just about anywhere within distance to a power outlet with some velcro if it can't just be sat on a table or something. My units typically look like this:

Though this one uses a Ubisoft camera (didn't wanna take down a PS3 eye for this pic so I pulled my crappiest unused USB cam from the closet. This camera is awful, but I got it for free so I can't complain, lol)