I keep my chickens as pets, and to observe genetics - I don't eat meat, but I do eat eggs. I have 67 pet chickens (!) currently, the most I have had at one time is 80. The layers and the retired layers plus a few meat-type hens and mixes I have taken as pets free range over six acres with a livestock guardian dog, but I have an all-rooster flock of twenty odd birds (everything from a Brahma to leghorns to bantams and several mutts) who are kept in a spacious (half acre) grassy run or they would cause havoc with the hen flock. I also have some hens and cocks in smaller runs, mostly bantams and silkies, these are my breeding birds and they are paired to produce specific ornamental traits in their offspring. Almost all of them have names (there are some who are virtually identical, and they are the"twins" or the "triplets" etc), and the oldest, a bantam rooster named Elliot, is fourteen. I have laying breed hens and notice they don't last as long as ornamentals and roosters always outlive the hens of any breed, but I do have several 7-9 year old layers. They produce about four eggs a year now, but as long as quality of life is good, this is their home.
I also have a small assortment of other supposed-to-be-eaten farm animals which I have made pets, including a steer bought at a 4-H auction, saved from becoming steak by his extremely friendly demeanor. The girl who raised him was too attached to see him sold for slaughter, and I overheard and did an impulse buy I don't regret. He is very sweet, and the girl still visits him.
I rehome excess birds from my hobby breeding programs as pets, they are very well socialized and I have no issues finding good homes for them.
I am competent at euthanizing birds when the time comes, but don't do so otherwise. The very old birds, if they haven't been on medication that I would worry might remain in their system, are given to a neighbor who does raise meat birds, and they become stew - which is fine by me, as it is a better use than they would get otherwise.
My personal mantra is kindness. For me, that's making everything a pet. I understand this is not possible or reasonable for all people, but it makes me feel fulfilled.