In a large bowl, combine flour, oats, baking powder, baking soda, and salt.
In a medium bowl, combine vanilla, butter, eggs, and sugar.
Pour wet ingredients from medium bowl into the bowl with dry ingredients. Gently combine ingredients. Do not overmix. Fold in blueberries, then spoon mixture into prepared cupcake liners.
Add water to the Instant Pot and insert steam rack. Place cupcake liners on top. Lock lid.
Press the Manual or Pressure Cook button and adjust time to 9 minutes. When timer beeps, quick-release pressure until float valve drops. Unlock lid.
Remove muffins from pot and set aside to cool 30 minutes. Serve.