Make the lemon curd: Combine the allulose, stevia, lemon extract, lemon zest, and eggs in a heavy medium-sized saucepan and whisk to blend. Add the coconut oil and salt. Place over medium heat and cook, whisking constantly, for about 12 minutes, or until the mixture thickens and coats the back of a spoon thickly (do not boil).
Strain the mixture through a fine-mesh strainer into a medium-sized bowl. Place the bowl in a larger bowl filled with ice water and chill, whisking occasionally, for about 15 minutes, until the lemon curd is cooled completely.
Add the cream and gelatin to the curd and stir to combine.
Pour the mixture into an ice cream machine and churn according to the manufacturer’s instructions. Store leftovers in a tightly sealed container in the freezer.