Earlier this month, Mets star Brandon Nimmo played Santa Claus at the team’s annual Kids Holiday Party at Citi Field, where he helped give out gifts to local schoolchildren. And the 26-year-old outfielder says he felt at home doing it. But Nimmo, who grew up in Wyoming, says it took a while to get used to New York. “You could fit my hometown in Citi Field, I’m pretty sure,” says Nimmo, now living in Long Island City with his wife, Chelsea. He tells The Post about his first trip to the Big Apple (when he was 18) and how he spends his off days and the offseason in the city.