Prep the Popcorn Base: Line two large rimmed baking sheets with parchment paper or wax paper. Spread the freshly popped plain or salted popcorn and broken pretzel pieces evenly across the baking sheets in a single layer. Discard any unpopped kernels.
Melt and Drizzle White Chocolate: Place the white chocolate melting wafers and coconut oil in a microwave-safe bowl. Microwave in 30-second intervals at 50% power, stirring thoroughly after each interval, until completely melted and smooth. Using a fork or small whisk, generously drizzle the melted white chocolate all over the popcorn and pretzels.
Add Mix-Ins and Set: Immediately scatter the pastel candy-coated chocolates and sprinkles over the wet white chocolate so they adhere as it cools. Dust lightly with a pinch of fine sea salt. Transfer the baking sheets to the refrigerator for 15 minutes, or let sit at room temperature for 30 minutes, until the chocolate coating sets completely firm.
Mix and Display: Once hardened, gently break the chocolate-drizzled popcorn into bite-sized cluster chunks. In a large bowl, gently toss the drizzled popcorn clusters together with the buttery caramel popcorn until evenly combined. Pour the mix into a tall, clear glass apothecary jar or decorative container. Set out a mini scoop and small treat bags alongside for seamless self-service!