Frigate NVR + Amcrest cameras. 100% local, private, on-device AI object recognition and classification. Can use a Google Coral USB TPU to speed that up. Runs on hardware as modest as a Raspberry Pi.
Empire Tech cameras are a bit better bang for your buck. The 4k models are great--be sure to read each model's strengths (low light, backlight, IR, near, far)
Frigate no longer recommends the Coral accelerator. I think Hailo is recommended now
Otherwise Frigate is great and integrates well with Home Assistant. I have a light on my office desk that comes on when a person is detected near the house, for instance
Without it, if you want to know when something is happening on camera, you have to use motion detection. Motion detection sucks. Everything sets it off. Shadows moving, insects... anything moving.
Object detection, and then human detection, is extremely useful. Thankfully thats become nearly trivia enough to happen on device, but even with just "dumb" cameras the open source, on network solutions are very good.
I would suggest Annke - They appear to be rebranded Ubiquiti/Amcrest cameras with modified Hikvision FW, with fully local capability and great quality (The $30 2k camera sells for $130 from Ubiquiti)
The other half, at least for Ring doorbells, is making it easy to get push notifications when button pressed, with instant two-way connection for chatting through the camera.
It's already hard enough as a "certified homelabber" to get these things set up and running.
I've found Reolink to be pretty much plug and play. Totally local. The NVR itself has PoE ports so all you have to be able to do is run a long ethernet cable.
I like Tp-Link Tapo for plug and play. They have some battery/wifi models that last quite a long time you mount with a magnet which is great for a temporary setup.
Security systems used to be 100x the cost (parts+install) before the cloud because you essentially needed a local NAS and to run a bunch of PoE enabled ethernet to each corner of your house.
Frigate no longer recommends the Coral accelerator. I think Hailo is recommended now
Otherwise Frigate is great and integrates well with Home Assistant. I have a light on my office desk that comes on when a person is detected near the house, for instance