Blend coconut milk, almond milk, agave, oil, vanilla extract, salt, and xanthan gum in a blender. Chill in the refrigerator for 2 to 3 hours. Once the ice cream base is chilled, run it in an ice cream maker according to machine instructions. In the meantime, make the other components.
To make the caramel sauce
In a small saucepan, over medium heat, heat brown sugar, margarine, salt, and nondairy milk, stirring frequently. Once mixture comes together, increase heat to medium-high for 1 to 2 minutes, until it begins to boil and the bubbles move into the center of the caramel. Remove from heat and let sit 15 to 20 minutes.
To make the pretzels
Melt the chocolate chips in a double boiler or microwave. Spread the pretzels on a parchment-lined baking sheet or plate. Pour the chocolate over the pretzels and turn with a spatula until pretzels are coated. Freeze until completely frozen and firm. Remove from freezer and transfer the chocolate pretzels to a plastic bag and place on a flat surface. Using the back of a spoon, hit the pretzels until they break into small pieces.
To assemble the Salted Caramel Ice Cream
Drizzle the caramel sauce over the ice cream and fold in the chocolate-covered pretzel pieces. Cover bowl with plastic wrap, making sure that the wrap is pressed onto the top of the ice cream. Store in freezer