Zest one lemon, juice them all, and strain juice into a small bowl to remove seeds and pulp. Set aside.

Place 6 eggs and 2 egg yolks into a large bowl (set extra egg whites aside). Using a whisk, or electric hand mixer on a low setting, blend eggs until no pieces of egg white are visible (about 30 seconds with hand mixer). Don't whisk/blend too long so not to introduce too much air.

Add lemon juice, lemon zest, and allulose to egg mixture. Blend until just combined. It will look very runny at this point but that's exactly what you want. Carefully pour filling into pie crust and transfer to oven. Bake 20-25 minutes or until filling is just set and starting to brown but still slightly jiggly in the center. Be careful not to over bake at this point. It'll go back into the oven.

Remove pie from oven and set aside. Increase oven temp to 425°F. While oven comes up to temp make the meringue.

Place egg whites in a large bowl. Use an electric hand mixer (with blenders cleaned after mixing filling) to beat whites until they are foamy (about 30 seconds). Add cream of tartar and beat until soft peaks form (about 2 minutes). Continue beating, adding allulose gradually, until stiff peaks form (about 2-4 minutes more).

Using a rubber scraper transfer meringue from bowl to top of hot pie. Spread meringue out evenly and use the spatula to make wispy peaks by pressing down gently and lifting straight up quickly all over the meringue. Place pie back in oven and bake another 8-10 minutes or until meringue begins to brown at the peaks.

Remove pie from oven. Let cool to room temp on the counter. Cover loosely with plastic wrap (or invert the plastic cover of the pie crust to use as a lid) and place in the refrigerator to cool completely, at least 2 hrs up to overnight. Slice into 8-12 servings (depending on how big you want your slices). Enjoy!