Combine the onion, garlic, soy sauce, 1/4 cup each vinegar and water, 1 tablespoon sugar and 1/2 teaspoon pepper in an Instant Pot. Stir in the chicken. Close the lid and turn the valve to the sealing position. Set the pot to cook on high pressure for 8 minutes.
Meanwhile, slice the cucumbers and finely chop the Fresno chile (remove seeds for less heat). Toss the cucumbers and chile with the remaining 2 tablespoons vinegar and 3/4 teaspoon sugar in a medium bowl. Season generously with salt and let marinate while you finish the dish.
Cook the rice as the label directs.
When the time is up on the Instant Pot, carefully turn the steam valve to the venting position and manually release the pressure. Open the lid. Change the cooker to the high sauté setting and simmer until the sauce thickens slightly, 12 to 15 minutes.
Stir the coconut cream into the chicken mixture. Divide the rice, chicken and cucumber salad among bowls.