Turn on oven to 350°F and line a 9" x 5" loaf pan with parchment. Mix oats into flour in 30 seconds with a high-speed blender.
Mix the dry ingredients—granulated sweetener, baking powder, sea salt, and pumpkin pie spice—for a few seconds. Set aside.
Mix pumpkin puree, eggs, avocado oil, and vanilla in a large bowl. Mix dry and wet ingredients into a thick batter.
Mix sugar, pumpkin pie spice, ground cinnamon, and a pinch of sea salt in a small bowl. Divide half the batter into the loaf pan.
Sprinkle cinnamon and sugar on bread batter. Sugar will seem excessive. Because it is. Cover remaining batter over cinnamon sugar in bread pan.
Make a large “S” in pumpkin batter with butter knife. It swirls cinnamon. Cover the loaf pan with foil and bake 40 minutes. Continue baking without foil for 10–15 minutes until bread is clean and golden brown.
Quick breads finish at 190–200°F in the centre. For an accurate reading, place the digital thermometer in the loaf's centre and wait until the numbers stop moving. Slice and serve pumpkin loaf after cooling.