Cook the raspberries, allulose, and lemon juice over medium heat for 6 to 8 minutes until thick and jammy. Press the mixture through a fine mesh strainer if a seedless swirl is preferred, then chill completely.
Melt the sugar-free chocolate chips with the heavy cream and butter over low heat until smooth. Refrigerate until firm, then form the mixture into small irregular truffle pieces and keep chilled.
Heat the heavy cream and almond milk for the ice cream until steaming. Whisk the allulose and egg yolks in a separate bowl.
Temper the yolks with about 1 cup of the hot cream mixture, then return everything to the saucepan. Cook over medium-low heat until the custard lightly coats a spoon.
Remove from the heat and whisk in the cream cheese, vanilla extract, and xanthan gum. Chill for at least 4 hours, then churn until thick and creamy.
Add the chilled chocolate truffle pieces during the final minute of churning. Layer the churned ice cream with ribbons of raspberry swirl in a freezer-safe container.
Freeze for 2 to 4 hours before scooping.