Hardware is completely proprietary and closed source. All camera communications go through a black box hub device which talks to Arlo’s services. There’s no public API for any part of the hardware or software chain.

In other words, unless you’re going to take the time to reverse engineer all of it, you’re completely at their mercy.

Even if you opt for local storage you’re still beholden to their black box hub because that’s the only thing the cameras will talk to, and their app because that’s the only thing that will talk to their hub. (HomeKit and other integration exists but it doesn’t provide the full functionality you get from the app, and still requires their hub.)