Whisk together the oyster sauce, soy sauce, nahm prik pao, and fish sauce in a small bowl.
Using your hands or a fork, gently break up any clumps in the rice until the grains are separate.
Heat vegetable oil in a 12-inch nonstick skillet over high heat until smoking.
Add the onion, bell peppers, and shiitake mushrooms and stir-fry, 3 to 4 minutes.
Add the pineapple and duck, and stir-fry for another minute.
Add the scallions, ginger, garlic, cilantro stems, and white pepper and stir-fry until fragrant and lightly golden, 30 to 60 seconds.
Add the rice to the wok and gently stir-fry, stopping occasionally so the rice has a chance to brown a bit until it has some crispy edges and is heated through, about 3 minutes. You should hear sizzling during the last minute or so.
Add in the sauce mixture and stir to combine.
Taste and adjust the flavor as necessary with more oyster sauce or nahm prik pao.
Take off the heat, add in the basil, and stir through.
Transfer the fried rice to plates or bowls and serve right away.