In large bowl, beat cream cheese and erythritol until smooth. Add sour cream, vanilla, and eggs and gently fold until combined.
Pour batter into 7-inch springform pan. Gently shake or tap pan on counter to remove air bubbles and level batter. Cover top of pan with tinfoil. Pour 2 cups of water into Instant Pot and place steam rack in pot.
Carefully lower pan into pot. Press the Cake button and press the Adjust button to set heat to More. Set time for 40 minutes. When timer beeps, allow a full natural release. Using sling, carefully lift pan from Instant Pot and allow to cool completely before refrigerating.
Place strawberries and blackberries on top of cheesecake and serve.