Place sugar and 2 cups water in a medium saucepan over medium-high heat. Scrape in vanilla bean seeds and add whole pod to pan. Bring to a gentle boil, stirring until sugar dissolves. Add apricots and cook until just tender and skin begins to pull away from fruit, about 2 minutes. Using a slotted spoon, lift apricots from syrup; transfer to a plate. Return syrup to a boil and cook until thickened slightly, 8 to 10 minutes. When apricots are cool enough to handle, peel away skins.
Preheat oven to 375°F. In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt. In another bowl, whisk together buttermilk, eggs, and 2 tablespoons melted butter. Add to dry ingredients and stir until just combined with a few small lumps remaining. Stir in blueberries.
Heat oil and remaining 1 tablespoon butter in a medium (10-inch) nonstick skillet over medium-high. Add batter to pan; spread to edges. Cook until set around the edges but still wet in the center, about 6 minutes. Transfer to oven and bake until puffed and set, 10 to 12 minutes.
Cut pancake into wedges and serve with pats of butter, poached apricots, more blueberries, and a drizzle of poaching syrup.