looking for easy-to-install backup camera for 2016 c

Pretty sure Toyota makes the only one that can work directly with their head unit. Not saying it will just work if you get one and plug it in, because I've never tried that.

What I can tell you is that the Toyota camera operates on 6 volts, and their head units are set to supply 6 volts.

Aftermarket cameras are set up to work on 12 volts, because aftermarket head units tend to supply 12 volts.

The Toyota camera is much more expensive than most aftermarket units.

So my suggestion is to get yourself an aftermarket head unit and an aftermarket camera. They'll be compatible with each other, and you'll gain a considerable technology upgrade for the car overall.

I have personally replaced the head unit in our c. Our 2018 model already had a rear vision camera from the factory, the 6 volt Toyota one. So I had to add in a voltage regulator to take the 12v out of my Sony deck and make 6v for the Toyota camera.

Replacing the head unit in a Prius c is about as easy as it gets in a modern car. We really like having CarPlay & Android Auto for navigation.

Crutchfield sold us the deck and parts we needed, and the system has performed perfectly for over 5 years now.

And just to add- removing the rear row headrests is a major upgrade in rear vision. We store ours under the front seats to have them nearby for when we need to put passengers in the back.