Preheat the oven to 400 degrees F (200 degrees C). Line a large baking sheet with parchment paper.

Combine whole wheat flour, all-purpose flour, sugar, baking powder, cardamom, lemon zest, baking soda, salt, and ginger in a large bowl. Grate in frozen butter using a box grater and toss until mixture resembles coarse crumbs.

Mix yogurt, cream, egg, and vanilla extract together in a small bowl. Add to the flour mixture to form a crumbly dough, stirring just until no dry clumps of flour remain. Stir in unthawed blueberries.

Pour crumbly dough onto the parchment-lined baking sheet. Press dough together firmly until it forms a cohesive 8-inch circle. Flatten top to ensure the circle is even. Cut into 8 triangular pieces. Arrange the pieces 1 inch apart on the same parchment-lined pan.

Whisk egg and water together in a small bowl for the egg wash. Gently brush over the top of each scone.

Bake scones in the preheated oven until tops are golden brown, 20 to 25 minutes. Let cool completely, about 30 minutes.

Use the back of a wooden spoon to press thawed blueberries through a fine-mesh strainer into a medium bowl to extract 2 or 3 tablespoons of juice. Discards skins and seeds. Whisk confectioners' sugar and lemon juice into the blueberry juice until smooth. Drizzle blueberry glaze over cooled scones.