You can probably find a visual walkthrough of the GUI by searching youtube.
There's a login page. After you authenticate, there's a live view page, a review/recordings page if you are recording to SD card in camera, and a few settings pages.
I'd say you could absolutely access the camera standalone, but at least the cameras I have don't do any detection or notifications. That's where the NVR comes in. I know reolink has cameras that do all of the above including AI detection.
If iMessages are e2ee and you aren’t using iCloud, is there any evidence your messages aren’t private? As far as I’m aware iMessage is considered a very secure messaging channel. It seems like most people distrust it due to the Apple affiliation. Not that I blame them, I feel the same about Google.