it's OK to use the for loop. You upload more than one picture at a time to make a three-dimensional array.
all you have to do is read the subscript of name,type,tmp_name,error,size in a loop.
$iTun0 is the beginning
then you execute update
else
execute insert

I wonder if this is what I mean?

$fileCount = count($_FILES['icon']['name']);
$files = [];

    for ($i = 0; $i < $fileCount; $iPP) {

      $file = $_FILES['icon']['tmp_name'][$i];
      $dest = '../../images/admin/product/' . $_FILES['icon']['name'][$i];

      move_uploaded_file($file, $dest);
      $files[] = $dest;
}

$first = true;
foreach($files as $file){
    if($first){
        $first = false;
        // update xxx
    }else{
        // insert xx
    }
}

$fileCount = count($_FILES['icon']['name']);

for ($i = 0; $i < $fileCount; $iPP) {

  $file = $_FILES['icon']['tmp_name'][$i];
  $dest = '../../images/admin/product/' . $_FILES['icon']['name'][$i];
  move_uploaded_file($file, $dest);

  if($i == 0){
     // Update  
  }else{
     // Insert 
  }  

}