How to clone elements in an array that will belong to the cloned element that were previously children of the outgoing element?

There is an element that is created via document.createElement, as well as an array of its children. Can you please tell me how to clone both an element and an array of its children, so that these children belong to the cloned element?

For example element and array:

HTML:

<div id="abc"><p id="p1">1</p><p id="p2">2</p></div>

JavaScript:

let el = document.getElementById("abc");

let arr = [];

if(el)
for(let child of el.getElementsByTagName("*")){
  if(child.textContent === "1") arr.push(child);
}

let elClone = el?.cloneNode(true);

//arr.cloneArrFrom(elClone) = [span#p1]???

How can I clone elements in an array so that they are children of node of the cloned element and not loop through all of them again over the cloned element?

I don’t want to constantly loop over the cloned element el.getElementsByTagName(“*”), is there any way to not do this in this case?

I will be grateful for the answer!