Whisk the flour, salt, and sugar in a bowl. Cut in the cold butter until pea-sized pieces remain. Sprinkle in ice water 1 tablespoon at a time until the dough holds together. Shape into a disk, wrap, and chill for at least 45 minutes.

Rinse the marionberries carefully, removing leaves, stems, or spoiled berries. Pat them dry with paper towels.

Roll the dough to about 1/8 inch thick and 12 to 13 inches round. Fit it into a 9-inch pie plate, trim to a 1-inch overhang, fold the edge under, and crimp. Refrigerate for at least 1 hour, or freeze for 30 minutes.

Whisk the flour, brown sugar, cinnamon, and salt together, cutting in cold butter until pea-sized pieces remain. Refrigerate until ready to use.

Combine berries with lemon zest and juice. Whisk 3/4 cup of sugar with tapioca flour and salt, then fold into berries. Taste and add remaining sugar if needed. Let sit for 10 minutes.

Preheat oven to 400°F and place a parchment-lined baking sheet on a rack. Spoon filling into the chilled crust and spread crumble on top.

Bake at 400°F for 15 minutes, then reduce to 350°F and bake for 40-45 minutes. Cool on a wire rack until room temperature, about 3 hours. Chill for cleaner slices if desired.