Agreed, that's the only way to build a secure system. I have some outdoor cameras but they are on a physically separate network and can't talk to anything.

Also, they are on ethernet but because they also support wifi I physically cut the antenna connections because I'm not about to trust the manufacturer of the camera to not try to exfiltrate something.

But sadly this is, while not difficult, too much for the non-techie person to do. So people just buy Ring cameras with all the associated privacy problems.

The worst is that while my system is secure, many of the surrounding neighbors have ring cameras outside so I can't protect from those!