I have chicken bones after being boiled down to mush.
Can they be crushed? Then what can I use them for?
Worms need calcium and sometimes they struggle to get enough. People recommend eggshells in the worm bin for that reason. You are not supposed to put meat in the worm bin (because of rats) but I think these bones are ok. They will fall apart pretty quick.
If you don't have a worm bin you could bury them in your garden. I am told tomatoes like extra calcium in their soil. Do an experiment and put them all by one tomato plant and see if that one is bigger. If you have kids the right age, show them what you are doing and maybe they will make it into a science fair project for next year.
Bone is not typically considered fit for human consumption. Cooked, they become dangerous. They are brittle and sharp and can puncture the intestines(source). Uncooked they become a pathogen risk, especially with chicken bones.
There was a time when people ate bone meal, presumably for calcium, but that is no longer considered a good practice. More reading about Bone meal from Wikipedia.
Depending on how long you cooked your bone broth, your chicken carcass still might have some flavor. After straining your first broth, add fresh water and more aromatics to the pot. Boil for a few more hours, and then blitz it with an immersion blender. Strain, yielding a thick creamy broth that makes a delicious bowl of ramen.
(Most of the actual bone meal will be strained out and can be added to your compost heap.)