great info. I cook liver and heart for my pups. I have never had chicken liver but I hear it’s mild (my only comparison is venison)Yes. It's all chicken meat. The neck is dark meat, the back can have some light and some dark. The gizzard and heart are kind of stringy dark meat, they are working muscles. The gizzard has a tough layer on it, you need to peel that off.
The liver has its own texture and flavor which many people don't like. Personally I like the liver as long as it is not overcooked. The day that I butcher my lunch is usually fried liver.
Dogs generally love liver, heart, and peeled gizzard.