Not sure how they wire up. i would assume 12 V for power are quite normal, but what kind of plug they come with may vary depending on the intended use.
I would contact seller and tell about your plans and options with his product.
I ran a 4 channel analog dashcam system back in the day plugged into my 2 DIN aftermarket head unit, so upon powering up my car / radio it would switch to the camera input on the AV in port, but i could then change away from that to play my MP3 files . disks or run the radio.
Normally the reversing camera connected on that AV in would be powered by the reversing light of your car, so change automatic to that input when you engage reverse and the radio sense a AV signal as now the camera have powered up and is transmitting, and switch back to whatever the head unity was doing when you take your car out of reverse and the camera turn off due to no power from the reversing light.
But as i had a constant AV signal coming from my analog DVR / dashcam and into the radio AV in i had to switch away from the AV in manually, which was quite easy and no hassle at all.