Preheat the oven to 350°F (177°C). Line a 9×5-inch loaf pan with parchment paper and set aside.
Grate the zucchini with a box grater and measure 1 cup of grated zucchini (about one small or part of a medium zucchini); set aside.
Place the quick oats, baking powder, ground cinnamon, and sea salt in a high-powered blender or food processor and blend on low for about 60 seconds, or until the oats form a fine flour.
In a large bowl, whisk together the Greek yogurt, egg, pure maple syrup, avocado oil, and vanilla extract until smooth.
Add the oat flour mixture to the wet ingredients and stir until combined, then fold in the grated zucchini until evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top. Tent the pan with aluminum foil and bake at 350°F for 50–60 minutes, or until a toothpick inserted in the center comes out clean.
Optionally check doneness with a digital thermometer; the center should register at least 190°F (88°C).
Remove the loaf from the oven and let it cool completely in the pan before removing and slicing.