Preheat the oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper and lightly grease it.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3 minutes.
Add the eggs one at a time, beating well after each addition.
Mix in the sour cream, lemon juice, lemon zest, and vanilla extract until fully combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Pour the batter into the prepared baking pan and spread evenly.
Bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool completely in the pan on a wire rack.
Once cooled, crumble the cake into a large bowl until fine crumbs form.
Melt 4 ounces of white chocolate chips in a microwave-safe bowl in 20-second intervals, stirring between each, until smooth.
Add about 2 tablespoons of the melted white chocolate to the cake crumbs and mix thoroughly until the mixture holds together when pressed.
Roll the mixture into 24 even-sized balls and place them on a parchment-lined baking sheet.
Insert a lollipop stick into each cake ball, pushing about halfway through.
Freeze the cake pops for at least 30 minutes to firm up.
While the cake pops chill, melt the remaining 4 ounces of white chocolate chips with the vegetable shortening in a microwave-safe bowl, stirring every 20 seconds until smooth.
Remove the cake pops from the freezer. Dip each cake pop into the melted white chocolate, allowing excess to drip off.
Immediately decorate with yellow sanding sugar and place one mini edible sugar pearl on each cake pop before the coating sets.
Place the decorated cake pops upright in a styrofoam block or cake pop stand to dry completely, about 30 minutes.
Once set, store the lemon cake pops in an airtight container at room temperature for up to 2 days or refrigerate for up to 5 days.