Preheat oven to 350°F (175°C) and grease a nonstick cake pan with butter or spray with baking spray. Whisk together almond flour, granulated sweetener, baking powder, poppy seeds, and salt. Tip: Sift the almond flour for a fluffier cake. Mix together avocado oil or pureed avocado, eggs, yogurt or sour cream, vanilla extract, lemon juice, and lemon extract. Add dry ingredients to wet and mix. The flavor of lemons and lemon extracts varies, so check the sweetness level of the batter. Pour into well-buttered or greased bundt pan and bake for 40-55 minutes until a knife or toothpick comes out clean. Let the cake cool for 10 minutes before flipping. For the glaze, add lemon juice to powdered sweetener and mix until desired sweetness and consistency is attained. Add a dash of poppy seeds to the glaze, if desired. Drizzle glaze onto cake. Top with raspberries, blueberries, or sliced strawberries (optional).