Melt one tablespoon of the butter in a Dutch oven or large pot over medium-high heat and add the bacon.Cook, stirring frequently, until crisp, 6 to 8 minutes. Using a slotted spoon, transfer the bacon to a paper towel-lined plate and set aside.Reduce the heat to medium and add the onion.Cook, stirring frequently, until softened, about 3 minutes. Add the garlic and cook 1 minute more. Do not brown.Stir in the orzo and cook, stirring frequently, until lightly toasted, 2 to 3 minutes.Stir in the broth, salt, pepper, and Cajun/Creole seasoning and bring to a boil.Reduce the heat to low, cover, and simmer, stirring once midway through, until the orzo is creamy and nearly tender, about 10 minutes.Stir the shrimp and peas into the orzo.Cover and cook over low heat until the shrimp are opaque throughout and the orzo is tender, about 5 minutes. Off the heat, stir in the remaining tablespoon of butter, the lemon juice, and chives. Right before serving, stir in the crispy bacon.Taste and adjust seasoning, if necessary, then spoon into bowls and serve.