Add the crust ingredients to a food processor. Pulse the walnuts for about 15-30 seconds until they are broken into small pieces.
Scoop the walnut crust into a 7-inch round cheesecake pan. Use a spoon to spread the walnuts around and cover the bottom of the pan. Then press the walnut using glass or bowl with a flat bottom to compact the crust. Any holes will fill in while doing this.
Place the crust in the freezer for at least 10 minutes while you make the cheesecake filling.
In a large bowl mix together the room temperature cream cheese, vanilla, salt, sour cream and sweetener with an electric mixer or whisk. When the filling is nice and smooth taste it to see if it is sweet enough. Add more sweetener if desired.
Next, mix the room temperature eggs into the filling ONE AT A TIME on LOW speed. Mix each egg for about 8-15 seconds if using an electric mixer. You only need to mix the filling until the egg is no longer visible.
Pour the cheesecake filling into the crust and smooth the top out.
Cover the top and bottom of the pan with first a layer of paper towels and then foil. The paper towels will make sure water doesn't pool on top of the cheesecake.
Add the strawberries and water to the bottom of the Instant pot insert. Using a trivet lower the cheesecake into the Instant Pot. Close the lid and turn the pressure valve to seal. Cook the cheesecake for 35 minutes on high pressure using the manual or pressure cook setting. Let the pressure release naturally. This will take about 30 minutes.
Remove the cheesecake from the Instant Pot and set it aside to cool completely. While the cheesecake is cooling, mix together the blueberries, blackberries, and raspberries in a bowl.
Strain the red strawberry liquid from the Instant Pot over the mixed berries while it is still hot. You can also blend the strawberries and liquid then pour the strawberries over the mixed berries. It is up to you.
Carefully mix the gelatin into the berries a little at a time so that it doesn't clump. You will want to do this while the liquid is still hot so that it will dissolve. Taste the topping and add sweetener to it if desired.
Wait until the berry mixture is cool, not hot, then pour the berries over the cheesecake that is still in the pan. Cover with foil and refrigerate overnight. The next day remove the cheesecake from the pan, top with whipped cream, and enjoy!