Preheat the oven to 425 degrees F (220 degrees C).

Roll pie crusts into 11-inch circles. Fit 1 crust into a 9-inch pie dish; place on a rimmed baking sheet. Cut 2nd crust into 1/2-inch wide strips; set aside.

Whisk together 1/2 cup sugar, 1/2 cup flour, and 1 teaspoon cinnamon. Cut in butter until topping resembles coarse crumbs; set aside.

Stir rhubarb, strawberries, 1 1/3 cups sugar, 1/4 cup flour, ginger, nutmeg, 1/4 teaspoon cinnamon, salt, and eggs together until well combined.

Spoon strawberry-rhubarb filling into pie shell; sprinkle crumb topping evenly over filling.

Moisten rim of crust with water. Lay two long strips of reserved cut pie crust in a cross pattern in center of pie. Alternate remaining horizontal and vertical strips across pie, weaving strips as you go; trim crust strips. Press strip edges into rim with flour-dipped fork to crimp edges.

Bake in the preheated oven for 10 minutes; reduce heat to 350 degrees F (175 degrees C) and continue to bake until filling bubbles and crust is light brown, 45 to 50 minutes more.