My guys love gibblets or gizzards. You can thin slice them but I just cut them in half and hand them out that way. Some of them like the dried meats that I dry out for the dog, but they prefer the ones they do for themselves ciao
giblets/gizzards are readily available at most grocery stores. they're usually packaged with hearts- a great source of taurine! They're tough to cut though and they can be an acquired taste to some furkids.