sort postmeta that is a serialized object by custom order of your choice - uksort function - custom index list order - always first

sort_by_order.php

<?php

class Sort_The_List {
  
  static public function get_postmeta_from_db( int $post_id ){
    $full_meta = [];
    $the_meta = get_post_meta( $post_id, '_your_meta_key', true );
    foreach( $the_meta as $key => $value ){		
			if( is_array( $value ) || is_object( $value ) ) {
				foreach( $value as $k => $v  ) {
					$full_meta[ $k ] = $v;
				}
			} else {
				$full_specs[ $key ] = $value;
			}
		}
    $full_meta = self::get_sorted_order($full_meta);  // magic happens here ;) 
		return $full_meta;
	}
  
	/*
  * uksort sort function - main function to call
  * http://php.net/manual/en/function.uksort.php
  */
	static public function get_sorted_order(&$arraytosort){
		uksort($arraytosort,"self::get_sorted_order_cmp");
	}
  
	/* 
  * the custom compare callback function for uksort 
  */
	static public function get_sorted_order_cmp($a,$b){
		/**
		 * Index of sorted 'key names' => 'values'
		 * Key name matches Items to sort Values
		 */
		$order = array(
      'Always First' => 0,
			'First Item' => 1,
			'Second Item' => 2,
			'Third Item'  => 3,
			'Fourth Item' => 4,
			'Fifth Item' => 5,
			'Sixth Item' => 6,
			'Seventh Item' => 7,
			'Eighth Item' => 8,
			'Ninth Item' => 9,
			'Tenth Item' => 10
		);
		return $order[$a] - $order[$b];
	}