So, back on topic.
I have one of these for myself, mostly just because there are idiot drivers and this will provide extra evidence if they cause an accident on me.
I have considered getting a dual camera one, not so much for the cabin, but to have a rear view of the idiot about to rear end you. There are some that have a remote wired input for one you can put in your rear glass.
Cables: You may want to think about routing, there are some videos showing how people route cables, cables hanging in the windshield are kind of odd and distracting to me. These things take power and the ones with batteries are nice, but they do not last long.
Arizona is hot. If you have a battery unit, it will age quickly and you will end up with a wired only camera soon, unless it has a slot for you to change the batteries.
Arizona is hot. Even some of the name brand ones will die if you leave them in your car in the summer.
Consider one that you can take out and put back easily.
Arizona is hot. Consider your mount. Generic sticky things will fall off.
Auto-on there are some cameras that turn on recording with the ignition. Most consumer versions turn on when you press it.
While live feed is interesting, it is a target for being hacked, if you care about privacy. Also, data is not cheap for live video feeds.
When I was reading about dashcams there were some recommendations for units using a capacitor instead of batteries for the AZ heat. I haven't decided on a model yet, but I do see the value of having one for evidence in the event of an accident. I have had a couple of cars try the swoop and squat in front of my truck on the 51 freeway.