Preheat oven to 375-degrees F
Line the bottom of a 9" pie plate with one of the two pie crusts. If using frozen fruit, quickly rinse off any ice that may have formed around the berries and drain completely.
Mix both sugars, tapioca, orange zest, orange juice, salt, and cinnamon, if using. Add huckleberries and one shredded apple (optional) and mix gently to combine.
Set aside to rest for 15 minutes to allow the tapioca to activate.
Meanwhile, cut the remaining pie crust into ¼" strips using a pastry wheel.
After the fifteen minutes are up, pour pie filling into the prepared pie crust and dot with butter.
Place the strips of dough in a lattice fashion over the pie and either tuck the ends of the strips under the bottom crust or fold the bottom crust over the strips and crimp.
Cover pie edges with foil or pie crust protectors. Brush with 1 tablespoon of milk and sprinkle with 2 teaspoons sugar. Bake for an hour, or until the mixture is thick and bubbly and begins to ooze out of the lattice crust. Remove the foil during the last 15 minutes.
Cool the huckleberry pie before slicing. Enjoy topping with vanilla ice cream.