Weigh or lightly spoon flours into dry measuring cups; level with a knife.
Combine flours, baking powder, baking soda, and salt in a large bowl; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal.
Combine pumpkin, yogurt, and 1 egg white, stirring with a whisk.
Add to flour mixture; stir just until moist.
Turn dough out onto a lightly floured surface; knead lightly 4 times with floured hands. Pat dough into an 8-inch circle on a baking sheet lined with parchment paper.
Cut dough into 12 wedges, cutting into but not through dough.
Brush remaining 1 egg white over top of dough.
Sprinkle dough with cheese and pumpkinseeds, pressing lightly to adhere.
Bake at 400 for 20 minutes or until golden. Slice scones along score lines with a serrated knife.