Preheat the oven to 180°C using conventional top and bottom heat. Grease a loaf pan and line it with parchment paper.
Whisk the eggs, Greek yogurt, honey, lemon zest, and vanilla extract in a large bowl until smooth.
Blend the oats into fine oat flour. Reserve approximately 1½ tablespoons for coating the blueberries.
Add the remaining oat flour to the wet mixture in two or three additions, stirring well after each addition.
Sift the baking powder over the batter and mix until evenly incorporated.
Toss the blueberries with 1 teaspoon of oil. Add the reserved oat flour and coat the berries evenly.
Gently fold the coated blueberries into the batter.
Transfer the batter to the prepared loaf pan and smooth the top. Use a greased knife to make a shallow line lengthwise down the center. Decorate with extra blueberries and oats if desired.
Bake for 40–43 minutes. The loaf is ready when a skewer inserted into the center comes out without wet batter.
Allow the bread to cool completely in the pan before lifting it out and slicing.