Order custom query by last word

custom-qorder.php

<?php
$args = [
    'posts_per_page'   => 10,
    'post_type'        => 'speaker',
    'meta_key'         => 'speaker-front-page',
    'meta_value'       => '1',
    'orderby'          => 'customq_last_word',          //<-- Custom ordering
    'order'            => 'ASC'
];

// query
$the_query = new WP_Query( $args );


// On functions.php
add_filter( 'posts_orderby', function( $orderby, \WP_Query $q )
{
    if( 'customq_last_word' === $q->get( 'orderby' ) && $get_order =  $q->get( 'order' ) )
    {
        if( in_array( strtoupper( $get_order ), ['ASC', 'DESC'] ) )
        {
            global $wpdb;
            $orderby = " SUBSTRING_INDEX( {$wpdb->posts}.post_title, ' ', -1 ) " . $get_order;
        }
    }
    return $orderby;
}, PHP_INT_MAX, 2 );