START: On a 6-quart Instant Pot, select More/High Sauté. Add the oil, onion and 1/2 teaspoon salt, then cook, stirring occasionally, until the onion begins to brown, 8 to 10 minutes. Stir in the garlic and cook until fragrant, about 30 seconds. Add the wine and cook, stirring, until almost fully evaporated, about 5 minutes. Add the chicken, orzo and broth; stir to combine, then distribute in an even layer.
Fast: Press Cancel, lock the lid in place and move the pressure valve to Sealing. Select Pressure Cook or Manual; make sure the pressure level is set to High. Set the cooking time for 6 minutes. When pressure cooking is complete, quick-release the steam by moving the pressure valve to Venting. Press Cancel, then carefully open the pot.
FINISH: Stir the mixture to combine, then re-cover without locking the lid in place and let stand for 5 minutes. Stir in the mint, arugula and lemon zest and juice. Taste and season with salt and pepper. Serve topped with feta.