In a saucepan over medium heat, stir together Greek yogurt, key lime juice, sweetener, and key lime zest. Cook for about 4 minutes, stirring continually. Remove from heat and pour mixture into 6 popsicle molds, dividing evenly.
In a small bowl, mix graham cracker crumbs, sweetener, melted butter or coconut oil, and salt. Sprinkle on top of each key lime pop, dividing evenly and packing down a little into the pop mold.
Place wooden sticks in the middle of each pop. Freeze for 4-6 hours until frozen solid.
Remove popsicles from molds by gently running the molds under lukewarm water, or letting set on the counter until they easily wiggle out. Enjoy immediately, or store popsicles in freezer for a future delicious dessert!
Note
If key limes are not available, regular limes will work for the lime zest.