Add half the strawberries to a heavy saucepan, place over medium heat, and cook until broken down and thickened, about 10 minutes. Let berries cool slightly.

Add the shredded apple to a large bowl, then add in cooked berries, remaining frozen berries, sugar, tapioca flour, and salt. Toss to combine.

Preheat the oven to 400 degrees F (200 degrees C). Grease the pie dish.

Lay 1 pie crust in the prepared pie dish, and crimp along the edges. Pour in the berry mixture and smooth it out. Gently lay the top crust over the berries, then crimp to the bottom crust edge. Pinch to ensure there are no gaps. Cut an X in the middle of the pie with a sharp knife.

Bake in the preheated oven for 15 minutes. Remove from the oven; reduce temperature to 350 degrees F (180 degrees C). Bake until filling is bubbling, about 30 minutes more. Remove from the oven to cool.

For the glaze, whisk confectioner’s sugar and milk together in a small bowl until smooth. Brush over cooled pie, then cover with sprinkles.