Fetch bookings for given product id and available comment data.

functions.php

<?php

$args = array(
    'post_type'  => 'bkap_booking', // Replace with your actual custom post type
    'meta_query' => array(
        'relation' => 'AND',
        array(
            'key'   => '_bkap_product_id',
            'value' => '123',
            'compare' => '='
        ),
        array(
            'key'     => '_bkap_additional_comment',
            'value'   => '',
            'compare' => '!='
        )
    )
);

$query = new WP_Query($args);

if ($query->have_posts()) {
    while ($query->have_posts()) {
        $query->the_post();
        
        // Your code to display or process the booking data
        $booking_id = get_the_ID();
        $product_id = get_post_meta($booking_id, '_bkap_product_id', true);
        $additional_comment = get_post_meta($booking_id, '_bkap_additional_comment', true);

        echo 'Booking ID: ' . $booking_id . '<br>';
        echo 'Product ID: ' . $product_id . '<br>';
        echo 'Additional Comment: ' . $additional_comment . '<br>';
    }
    wp_reset_postdata();
} else {
    echo 'No bookings found.';
}