Cook the bacon pieces in a Dutch oven over medium heat until crisp, about 6 minutes. Remove with a slotted spoon and transfer to a paper-towel-lined plate. Discard all but 1 tablespoon of bacon fat.

Add the butter to the pot and let it melt. Set aside 1/4 cup of the green onion tops for serving, then add the remaining green onions and celery. Cook, stirring occasionally, until tender, about 3 minutes. Stir in the garlic, salt, and black pepper and cook until fragrant, about 30 seconds.

Sprinkle the flour over the onion mixture and cook, stirring constantly, for 1 minute. Slowly pour in the nonfat milk a few splashes at a time, stirring out any lumps. Stream in the rest of the milk, then add the corn kernels, cream-style corn, and cayenne. Stir and bring to a gentle boil. Let bubble until thickened, about 5 minutes.

Stir in the thawed shrimp and continue cooking just until the shrimp are pink and opaque throughout, about 3 minutes. Remove from the heat, then stir in the fresh thyme and half-and-half.

Serve hot, topped with reserved crispy bacon, green onion tops, and a dash of hot sauce as desired.