When it comes to authenticity... well, Trump has this weird reality-warping power where sometimes he can be totally sincere and yet you know he's in on the joke.
I keep thinking of that campaign stunt where he worked at McDonalds. He openly acknowledged it was a stunt, but at the same time he loves McDonalds, he eats their stuff all the time (much to his doctor's distress I'm sure), he knows every item on the menu. So when you saw that footage of him putting on the apron, chatting to the staff, learning how to work the fryer, serving at the drive-through window, there was a kind of childlike joy on his face that you couldn't fake.
Imagine Gavin Newsom flipping burgers and the absurdity is too much to bear.
A bunch of Republican candidates tried to ape the Trump style while keeping the old corporate GOP policies and it didn't work. Vance got it the right way round by having the populist agenda but a more polite style that's authentic to Vance.
One of my favourite US senators, for pure entertainment purposes, is Markwayne Mullin of Oklahoma. He's the only Native American senator. I think he's the only senator without a college degree, and one of very few who isn't a lawyer. He's a construction industry guy, and looks it. He's brash and rude and often gets into shouting matches with Bernie Sanders. He's kind of an insult comedian moonlighting as a senator.
Mullin is a useful yardstick for saying, well this guy can get away with it but I'm not this guy. A slick coastal Democrat trying to be as rude and abrasive as Mullin, without Mullin's great comic delivery, would just look stupid.