Quails. Even cuter than chickens and much more easy to keep. Might be one of the easiest to keep animals overall. Not even ant colonies, fish, cats or dogs are as happy with as little as quails.

Housespiders and cacti might be easier.

You need to use quail proof feeders, tho, or you're going to spend a fortune on kitchen scraps or whatever you intend to feed them. They eat just about anything peckable except oats (if you didn't end up with picky ones). Cookef rice, seeds, peas, boiled eggs, sometimes nibbling on each other (-.-), or dirt cheap quail feed. Also mealworms ... its catnip for quails.

> You may have to euthanize a chicken, likely by hand (literally) via cervical dislocation.

I recommend cutting the head off with a pair of high quality, large and well maintained scissors.

Put a bucket in front of you, put the scissors from behind on the neck, just below the head, and cut in a single strong motion.

The lil birdy will not understand what is happening and wont feel uncomfortable during the process. Its head then looses consciousness in sbout 15 seconds, compared to about 30 seconds for the cervical dislocation method. (It'll loose the ability to feel pain MUCH faster than 15s, but I dont think we know how quickly. But probably faster than it'll realize that there's pain in the first place. You've probably cut yourself before and noticed that the pain only kicks in after a moment.)

It is also way easier to not screw up. Just remember to ALWAYS cut the head off completely, as fast as possible. Lil birdie wont die from bloodloss, but sudden loss of spinal fluid, which is WAY faster.

The cervical dislocation method is also very effective, but also much easier to screw up, a bit more uncomfortable for the birdy and could introduce quite some anxiety for the birdy if you hesitate for even but a moment.

On the other hand the cute little critters dont understand how scissors work or what they're for. Even if the method is much less pretty, it's by far the most peaceful method for the birdy.