If using drumsticks, cut each into 2–3 pieces; leave wings or breasts whole.
Turn Instant Pot to Sauté and heat until hot, then add the oil.
Sear the chicken in the hot oil until lightly browned on both sides; work in batches if needed to avoid crowding. Use a nonstick skillet for searing if the chicken sticks.
Add the sliced ginger to the pot and sauté briefly until fragrant.
Pour in the soy sauce, sweet soy sauce (kecap manis), ground white pepper, sesame oil, and water; stir to combine.
Close the lid, set the valve to sealing, select Manual/High pressure, and cook for 8 minutes.
When the cook time ends, perform a quick release; when the valve drops, carefully remove the lid.
Stir in the scallions and serve immediately. If the sauce is too thin, turn on Sauté and reduce for about 1 minute until slightly thickened.