Some children are deeply fascinated with just about anything more than food. My guess is that they're just bright (maybe brighter than average), curious kids who have never been really hungry.
I'm sure your son will learn to eat on his own if you stop feeding him. There could be a stressful adjustment period while he learns to recognize what hunger is. He could have emotional meltdowns from low blood glucose, trouble sleeping through the night, or other problems while he adapts. You could feel stressed that he's "not eating enough." He could lose a little weight. He could feel abandoned and jealous (and indeed, you are changing your behavior toward him so you can give more attention to the baby) and behave accordingly. If you are prepared to face all this, you could just stop feeding him. Or you might try phasing out the feeding over a week or two and soften the consequences a bit.
Since his stress would be stressful for you, too, you might want to consider another option that would free you up quite a bit. For many toddlers, grazing at will throughout the day is more natural than sitting through bigger meals. (In some indigenous societies, this is still the norm.) Have you considered leaving out a small selection of veggies, fruits, cheese, toast or crackers, scrambled eggs, leftovers and other healthy finger foods for him to nibble? This was a pretty helpful option for my grandboy, who would hardly feed himself at all when younger, and was very restless sitting through meals. We'd poke food into his mouth at frequent intervals through the day, and he'd nibble things he particularly liked if it was easily available. He's getting quite a bit better at 3 1/2, and without his parents making a battle out of it. The adults in his life have coaxed him at every meal to take a few bites on his own (but we don't have younger siblings to care for, so it's easier).
There are some likely pluses to a kid who won't feed himself, too. In my grandson's case, he was never inclined to put things in his mouth that didn't belong there. He's a slim, healthy weight. He doesn't eat compulsively to comfort himself, or out of boredom. He will eat just about anything an adult feeds him while he's preoccupied, which means he gets a good, balanced diet and has learned to accept a wide variety of foods. Though I'm not the one who has to be sure he stays well-nourished every day, I love it that his relationship with food is almost casual, and that he likes almost every vegetable and fruit. Now he'll carry around a chunk of cucumber, cheese, apple, or sweet pepper, and munch away while he plays.
Unless the grownups make an issue of some behavior that can arguably be seen as completely normal, I disagree that it's a "power struggle." Kids that young behave mostly out of pure, spontaneous impulse. It's adults trying to keep to a schedule, establish rules, or even just get some sleep, who initiate most power struggles in very young children, by frustrating a child's natural inclinations. Kids aren't puppets, and do have feelings and needs that sometimes adults either don't recognize or assume shouldn't be there.
But since adults have more power and the imagination to find other options, we can often come up with solutions to these problems that meet our needs AND the child's. Good luck, C.. I hope you find a solution that doesn't unsettle the family.