Clean up unused Wordpress attachments

unused.php

<?php

//1. Get all attachment IDs
//2. Check if the ID appears as a simple meta value, or as a meta value like "[id]" (including quotes, to catch serialized values) or like wp-image-[id] (for wysiwyg ACF fields and such)
//3. Check if the ID appears in post_content like wp-image-[id]
//TODO - WordPress galleries. N/A in my case but probably needs its own check.

//If an ID does not appear in the above scenarios, get it gone.

require_once('wp-load.php');

//switch_to_blog(10); //if on multisite, work on a specific blog

global $wpdb;

$rows = $wpdb->get_results('SELECT ID from ' . $wpdb->prefix . 'posts WHERE post_type = "attachment"');
echo 'Total: ' . count($rows) . "\n";

$not_found = [];

foreach($rows as $row){

    $id = $row->ID;
    $found = false;

    $content_like = '%wp-image-' . $id . '%';

    $sql = 'SELECT post_id FROM ' . $wpdb->prefix . 'postmeta WHERE meta_value = ' . $id . ' OR meta_value LIKE "%\"' . $id . '\"%" OR meta_value LIKE "' . $content_like . '"';
    //echo $sql . "\n";
    $featured = $wpdb->get_results( $sql );
    if(!empty($featured)) $found = true;

    if(!$found){ //try to match in post content
        $post_content = $wpdb->get_results('SELECT * FROM ' . $wpdb->prefix . 'posts WHERE post_content LIKE "' . $content_like .'"');
        if(!empty($post_content)) $found = true;
    }

    echo "$id " . ($found ? 'found' : 'not found') . "\n";

    if(!$found) $not_found[] = $id;

}
echo 'Found ' . count($not_found) . ' possibly unused attachments';

//optionally output to a file rather than immediately delete
//file_put_contents('not_found.json', json_encode($not_found));

foreach($not_found as $id){
    echo get_the_title($id). "\n";
    wp_delete_attachment($id,true);
}

Also need to look for image URLs in case they are embedded that way