So in objective POV, this:
Karen gripped the steering wheel so hard that her nails dug into her palm. The welling blood and subsequent pain barely registered. Screw Chad. He was going to get what was coming to him. She glanced at the bag. Good. The gun wasn't showing.
Would read like this:
Karen gripped the steering wheel hard. Her nails dug into her palm. Blood welled. She glanced at the bag. The gun wasn't showing.
The POV can't get into Karen's head or detect emotion. So it can see blood welling from her palms, but it can't detect the "so hard" part or understand that the character is under duress. And it can see her looking at the bag and report that a gun isn't showing, but it can't call it "good." Or bad. It can only report the events objectively. The inner monologue part about Chad wouldn't be there obviously. No thoughts of any kind are allowed. It's a cool POV but gets cumbersome in a hurry.