vitas2008

const result = arr2.map(function(n) {
  return Object.fromEntries(this.map(m => [ m[1], n[m[0]] ]));
}, arr1.flatMap(Object.entries));

const keys = Object.entries(Object.assign({}, ...arr1));
const result = arr2.map(n => keys.reduce((acc, m) => (acc[m[1]] = n[m[0]], acc), {}));