Prep the caramel, optional but classic: In a small saucepan over medium heat, melt 3 Tbsp powdered allulose with 1 Tbsp water and the molasses drop. Cook 3-4 min until amber. Pour into a 7-inch flan mold; swirl to coat the bottom.
Blend the custard: Combine coconut milk, coconut cream, eggs, erythritol, vanilla, and salt. Blend 15 sec until smooth and a little frothy.
Fill mold & cover: Pour custard over the set caramel. Cover tightly with foil.
Pressure-cook: Pour 1 cup water into the Instant Pot. Place the trivet in, lower the mold onto it. Lock lid; set High Pressure 20 min. Allow 15 min natural release, then vent remaining steam.
Chill: Lift the mold out, uncover, and let cool 15 min. Refrigerate at least 4 hours, overnight best. To unmold, run a thin knife around the edge and invert.