You could always invest in IP cameras, and manage where the data goes yourself. No reason a 24/7 video stream of your home needs to be sent to a big tech company's data centers, anyway, or any data center for that matter.
I have a variety of WiFi cameras, all of which are on a dedicated WiFi network that cannot access the internet. I use Zoneminder to handle the recording, motion detection, etc. Zoneminder is pretty versatile, but it’s ultimately up to the camera to provide a compatible method of access - RTSP works well for cameras that support it, but if you have a URL on the camera that will return a JPEG that will work too.
Most of my cameras are low-end D-Link models, they work fine with Zoneminder. I recently got an Amcrest camera which, after some cajoling, works very well with Zoneminder. Using a JPEG URL that Zoneminder polls never worked for some reason, but RTSP worked perfectly.
If you want to go this route, look for evidence that other people have gotten the model you’re interested in to work with software like Zoneminder, Blue Iris, or iSpy. Generally this means that the camera supports open standards that you can use in your system.
If you don’t want to go the Zoneminder route, some cameras can do a lot of the work internally. All of my cameras, for example, have some degree of motion detection and the ability to upload files to an FTP server or send an email. The biggest challenge here is that none of these cameras can be configured to do this without either a Java Applet or a vendor-provided browser plugin to view the live video and define the detection zones and parameters.
> All of my cameras, for example, have some degree of motion detection and the ability to upload files to an FTP server or send an email.
Am I missing something?
Upon rereading my comment, it could have been structured differently to make that clearer.
For my wife, who's less tech saavy, I keep a couple nest cams handy :)