vue-wp/plugins/cia-endpoints/includes/class.make-oneofeach.php

<?php
// include('formats.php');

class Make_One_Each_Endpoint extends WP_REST_Controller {
    /**
     * Register the routes for the objects of the controller.
     */
    public function register_custom_route($route) {
        $version = '2';
        $namespace = 'craft/v' . $version;

        register_rest_route( $namespace, '/' . $route, [
            array(
                'methods'  => WP_REST_Server::READABLE,
                'callback' => array( $this, 'get_all_items' )
            ),
        ]);
    }
    public function get_all_items( $request ) {
        $args = array(
            'numberposts' => 1,
        );

        return new WP_REST_Response( $this->prepare_all_items_for_response($args), 200 );
    }
    public function prepare_all_items_for_response( $args ) {
        $collection = array();
        $types = [
            'artist',
            'episode',
            'event',
            'exhibition',
            'guide',
            'object',
            'publication',
            'technique',
            'short',
            'post',
        ];

        $q = [];
        foreach($types as $post_type) {
            array_push($q, new WP_Query(array(
                'numberposts' => 1,
                'post_type' => $post_type,
                'post_status' => ['publish'],
            )));
            array_push($q, $post_type);
            
            $found_post = $q[0]->get_posts();

            $formatted = default_post_format( $found_post, false );
            $formatted['tried'] = $q[1];
            array_push($collection, $formatted);
        }
        wp_reset_postdata();

        return $collection;
        // return $types;
    }
}

?>