Some thoughts...
Diced turkey - this might not turn out like you think. I speak from experience. It was rather hard and wouldn't rehydrate all the way. Ground, then cooked turkey is much, mucccchh better.
Cranberry sauce - Yup! I've never made a fruit rollup out of it but I have done dried cranberry sauce. Even before you rehydrate it it's still tasty
Stuffing - IF it doesn't contain a ton of fat, you could dehydrate it but one would have to ask, "What's the point, when you can just open a box of Stove Top..."
Mashed potatoes - Same problem with the fat. You can dehydrate them but you'll have to watch out for the fats so that it doesn't spoil before you get to use it. If I did fully made mashed potatoes it would still end up in the freezer. Again, "What's the point, when you can just open a pouch of [fill in the blank] mashed potato flakes..."
Yams/Sweet Potatoes - Totally! Make Bark as WM said. Goes great in lots of things or you could rehydrate them piping hot, throw in some walnuts and mini marshmallows and have some candied yams right on the trail!! Yum!!
Veggies - All those will dehydrate just fine. Go right ahead.
Pie - Would you really have any left over?
Gravy - Not that I know of. Doesn't mean you couldn't try but I'd rather just bring a pouch and make it on the trail. It's the fat that worries me.
My main theme here is to watch out for the fat. If it doesn't have fat, you're probably fine. Even a little fat, no problem. Above all, have fun and enjoy!!