Pulse 3/4 cup pistachios in a coffee grinder until finely ground. Transfer to a blender.
Pulse flax seeds in a coffee grinder until finely ground. Add to the blender.
Pour coconut milk into the blender. Add vanilla extract, stevia powder, xanthan gum, coconut oil, almond extract, and black salt; blend until very smooth, about 2 minutes.
Transfer blender container to the freezer to chill mixture briefly, about 15 minutes.
Pour mixture into an ice cream maker and churn according to manufacturer's instructions, adding 1/2 cup chopped pistachios during the last few minutes of churning. Transfer to a lidded container before serving.
