Stir together the fire-roasted crushed tomatoes, ginger, garlic, garam masala, and salt (if using) in the Instant Pot.
Nestle the chicken thighs into the tomato mixture. Lock the lid and set to cook on high pressure for 10 minutes.
When cooking is complete, press 'cancel' and let the pressure naturally release for 10 minutes, then carefully quick-release any remaining pressure.
Remove the cooked chicken from the pot and chip with a pair of kitchen scissors, or shred with two forks.
Stir in the butter and cream. Return the chicken to the pot.
Serve over rice with plain yogurt, chopped or thinly sliced cucumbers, lime juice, cilantro, and/or naan bread as desired.