Line a 9-inch springform pan base with parchment. Lightly grease the sides.
Stir graham crumbs, 3 tbsp sugar, salt, and melted butter until evenly moistened.
Press crumbs firmly into the pan bottom. Chill while you make the filling.
Drain crushed pineapple very well. Squeeze dry with paper towels to remove excess juice.
Bloom gelatin by sprinkling it over cold water in a small bowl. Let stand 5 minutes.
Warm bloomed gelatin gently in the microwave 10–15 seconds to dissolve. Cool briefly.
Beat softened cream cheese and 2/3 cup sugar until smooth and fluffy, about 2 minutes.
Mix in sour cream, vanilla, and lemon juice until silky.
Stream in the dissolved gelatin while mixing on low until fully incorporated.
Whip heavy cream with powdered sugar to stiff peaks. Fold into the cheesecake mixture.
Fold in the well-drained pineapple. Do not overmix.
Spread filling over the crust. Smooth the top. Cover and chill 4–6 hours, or overnight.
Top with extra pineapple before serving. Slice with a hot, dry knife for clean cuts.