So which camera brand has adequately designed software? It’s hard to know as a consumer what to trust or not trust, because how do you evaluate the quality of their work when the device SEEMS to work as expected? Is Ring the only choice?
If you don't want untrustable black boxes hanging around, then your options become pretty limited.
You can DIY something with an SBC like a Raspberry Pi or whatever. You can hang USB cameras off of your computers like it's 2002 again. You can try to find something that OpenIPC or thingino or whatever supports. (You'll never finish with this project as the years wear on, the hardware fails, product availability ebbs and flows, and the scope changes. Maybe that sounds like a fun way to burn time for someone, but it doesn't sound like fun to me.)
Or, you can accept that the world is corrupted -- and by extension, the cameras are also all corrupted.
The safe solution is then actually pretty simple: Use wired-only cameras that work with Frigate (or whatever your local NVR of choice may be), keep them on their own private VLAN that lacks Internet access, and don't worry about it.
The less-safe solution is also pretty simple: Do what everyone else is doing, and just forget the problem exists at all. Switch your brain off, buy whatever, and use it. (And if there's an area that you don't want other people to see, then: Don't put a camera there.)
(We probably are not as interesting as we may think we are, anyway.)