I didn't found any better than write this script, hope it help someone:

const getLastChildren = (parent: Element): Element[] => {
  return Array.from(parent.children).reduce<Element[]>((acc, node) => {
    const children = Array.from(node.children);
    if (children.length === 0) {
      acc.push(node);
      return acc;
    }
    return [...acc, ...getLastChildren(node)];
  }, []);
};

(without typescript):

const getLastChildren = (parent) => {
  return Array.from(parent.children).reduce((acc, node) => {
    const children = Array.from(node.children);
    if (children.length === 0) {
      acc.push(node);
      return acc;
    }
    return [...acc, ...getLastChildren(node)];
  }, []);
};