Preheat oven to 400 degrees.
Place bacon strips on parchment paper lined sheet tray. Bake at 400 for about 15 minutes until bacon is crisp but not brittle. Reserve bacon grease.
Make green sauce
Cook tomatillos, zucchini, onion, lime juice and salt and pepper in a 2-quart saucepan over medium heat. Cook about 5 minutes until tomatillos lighten in color and soften slightly. Transfer to food processor.
Add garlic, cilantro, xanthan gum to the cooked vegetables in the food processor. Pulse to chop slightly. Drizzle olive oil into mixture while food processor is running to reach desired consistency. Set aside.
Make chipotle sauce
Add butter, tomato puree, chipotle pepper, adobo sauce, smoked salt and cumin into a 1-quart saucepan. Cook over medium heat, stir as needed, until flavors blend, about 5 minutes.
Drain bacon fat into small skillet, Saute chard, and bacon pieces. Cook untill tender. Sprinkle with red pepper flakes.
Grill oysters in shells over medium high heat for about 3 minutes until they begin to bubble. Remove from heat. Spoon out oysters onto a plate. Be careful to reserve juice.
Add greens to shell. Return oysters. Spoon on chipotle sauce. Return to grill and cook an additional 3 to 4 minutes until hot and bubbling and thoroughly cooked. Remove from heat. add aadditional sauce if desired. Top with pepitas. Serve with green sauce on the side.