No, the power comes from the head unit. The head unit controls when the rear camera is powered. You can have a head unit that turns on the rear camera when it wants.
I bought it on AliExpress. I can't fully recommend it because the holes were advertised to fit and they didn't. I don't *not* recommend it, but I can't fully endorse it here.
sorry I might be misunderstanding, the screw holes didn't line up and I didn't feel like buying another camera so that was my way of adapting I considered a camera that bolts to the back of the license plate but I didn't to make holes in the Cayenne body for the wire