Combine the blueberries, sugar, lemon juice, lemon zest and cornstarch in a bowl and mix well. Set aside.
Mix together the lemon cake mix, butter and milk until a dough forms.
Place half of the blueberry mixture in a dish that can be inserted into the Instant Pot.
Place half of the dough over top of the blueberries.
Cover with half of the oats.
Put 1 cup of water in the bottom of the Instant Pot insert and place the trivet inside.
Place the dish on the trivet, lock the lid and seal the valve. Pressure cook on high for 25 minutes.
Let the pressure release naturally for 10 minutes then use the quick release to release any remaining pressure.
Repeat with the second half of the mixture.
Place the cobbler(s) under the broiler, watching them carefully, and broil until the oats turn golden brown and the crust is slightly bubbly. It should take about 5-10 minutes.
Let the cobbler rest for 30 minutes and serve topped with ice cream or homemade whipped cream.