Preheat oven to 350 degrees F.
In a bowl, whisk together eggs, sweetener, sour cream, and salt.
Slowly whisk in lemon juice and lemon stevia.
Pour filling into pre-baked pie crust.
Place pie onto a baking sheet and cover around the crust with aluminum foil.
Bake until barely set, about 30-35 minutes. Center of pie will still jiggle slightly.
Cool pie completely before adding topping.
To make topping, place the water into a small saucepan and sprinkle over the gelatin.
Heat on low, stirring constantly until gelatin is dissolved. Set aside.
Pour heavy cream into a stand mixer with vanilla stevia.
Whip until peaks form.
Slowly pour in the gelatin mixture.
Spread this over the cooled lemon pie.
Refrigerate 1 hour and up to a day, loosely covered.
Top with lemon zest if desired when serving.