What ho one and all,

My recently acquired 2015 Mazda 3 does not have a reversing camera and I plan to fit one, just for the convenience.
Doing a lot of Google research and that leads to confusion.
Apart from the obvious camera, does one wire it directly to the screen? Or can one use the multi-cable harness thing to connect to the sockets in the rear and then upon rebooting the car, everything works? (as some Youtube videos show)

Thanks and toodle pip