Why not feed chickens food off plates? I can't think of a better use on the planet (including composting) to properly manage food waste.
People are all over the map about this issue. I have a friend who has a flock of around 13, 4 of which are 11 years old. They do have free access to commercial feed, but are given absolutely everything and anything that comes out of the kitchen plus excess bread discarded by a bakery at the end of the week. Many people stop by and dump their waste in the run as well, at any given time there have been whole rotten onions, banana peels with the stickers on, leftover spaghetti, whole potatoes, whole raw carrots, even avocados! There are empty dirty containers and tupperware lids all over the run, the water is usually disgusting, and I just don't get it, lol.
I just can't "unknow" the good advice from people here, so I scrub the water buckets, pick up the poo, provide all flock ration with oystershell on the side, limit treats, provide protected pasture forage, and put them to bed at night in a secure coop with excellent ventilation and electric fence backup!
When I first met this woman, she mixed scratch into the layer feed, a huge no no from the experts everywhere. Even then she had old chickens. I try to do everything "right" but can't seem to keep more than 3 at any given time when my goal is to have 6 or 7. The oldest I've had was 4 years old.

Good luck with your chickens, use your own instincts, try stuff out and see how it goes!