A tiny little article plugin to demo Custom Post Types code to almost match Extended CPTs (no sortable admin columns or filters, and no "At a Glance" entry.

pixie-article.php

<?php

/**
 * @link              https://deliciousbrains.com/blog/
 * @since             1.0
 * @package           Pixie_Article
 *
 * @wordpress-plugin
 * Plugin Name:       Pixie Article
 * Plugin URI:        https://deliciousbrains.com/blog/
 * Description:       A tiny little article plugin to demo Custom Post Types.
 * Version:           1.0
 * Author:            ianmjones
 * Author URI:        https://profiles.wordpress.org/ianmjones
 * License:           GPL-2.0+
 * License URI:       http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain:       pixie-article
 * Domain Path:       /languages
 * Network:           False
 */

// If this file is called directly, abort.
if ( ! defined( 'WPINC' ) ) {
	die;
}

function pixie_article_activation() {
	pixie_article_loaded();
	flush_rewrite_rules();
}

register_activation_hook( __FILE__, 'pixie_article_activation' );
register_deactivation_hook( __FILE__, 'flush_rewrite_rules' );

function pixie_article_loaded() {
	load_plugin_textdomain(
		'pixie-article',
		false,
		dirname( plugin_basename( __FILE__ ) ) . '/languages/'
	);

	$labels  = array(
		'name'               => __( 'Pixie Articles', 'pixie-article' ),
		'singular_name'      => __( 'Pixie Article', 'pixie-article' ),
		'menu_name'          => __( 'Pixie Articles', 'pixie-article' ),
		'add_new'            => _x( 'Add New', 'Pixie Article', 'pixie-article' ),
		'add_new_item'       => __( 'Add New Pixie Article', 'pixie-article' ),
		'edit_item'          => __( 'Edit Pixie Article', 'pixie-article' ),
		'new_item'           => __( 'New Pixie Article', 'pixie-article' ),
		'view_item'          => __( 'View Pixie Article', 'pixie-article' ),
		'search_items'       => __( 'Search Pixie Articles', 'pixie-article' ),
		'not_found'          => __( 'No pixie articles found', 'pixie-article' ),
		'not_found_in_trash' => __( 'No pixie articles found in Trash', 'pixie-article' ),
		'parent_item_colon'  => __( 'Parent Pixie Article:', 'pixie-article' ),
		'all_items'          => __( 'All Pixie Articles', 'pixie-article' ),
	);
	$options = array(
		'labels'          => $labels,
		'public'          => true,
		'hierarchical'    => true,
		'menu_position'   => 6,
		'menu_icon'       => 'dashicons-media-document',
		'capability_type' => 'page',
		'supports'        => array( 'title', 'editor', 'thumbnail' ),
//// To re-implement admin_cols and admin_filters with stock WordPress API would require too much code to show here.
//		'admin_cols'    => array(
//			'pixie_article_audience' => array(
//				'taxonomy' => 'pixie-article-audience',
//				'title'    => _x( 'Audience', 'Pixie Article Taxonomy', 'pixie-article' ),
//			),
//			'post_date'              => array(
//				'title'      => __( 'Created', 'Date', 'pixie-article' ),
//				'post_field' => 'post_date',
//			),
//			'post_modified'          => array(
//				'title'      => __( 'Modified', 'Date', 'pixie-article' ),
//				'post_field' => 'post_modified',
//			),
//		),
//		'admin_filters' => array(
//			'pixie_article_audience' => array(
//				'taxonomy' => 'pixie-article-audience',
//				'title'    => _x( 'Audience', 'Pixie Article Taxonomy', 'pixie-article' ),
//			),
//		),
////
		'has_archive'     => true,
		'rewrite'         => array(
			'slug'       => 'pixie-articles',
			'with_front' => false,
		),
	);
	register_post_type( 'pixie-article', $options );

	$taxo_labels  = array(
		'name'                       => __( 'Pixie Article Audiences', 'pixie-article' ),
		'singular_name'              => __( 'Pixie Article Audience', 'pixie-article' ),
		'search_items'               => __( 'Search Pixie Article Audiences', 'pixie-article' ),
		'popular_items'              => __( 'Popular Pixie Article Audiences', 'pixie-article' ),
		'all_items'                  => __( 'All Pixie Article Audiences', 'pixie-article' ),
		'parent_item'                => __( 'Parent Pixie Article Audience:', 'pixie-article' ),
		'parent_item_colon'          => __( 'Parent Pixie Article Audience:', 'pixie-article' ),
		'edit_item'                  => __( 'Edit Pixie Article Audience', 'pixie-article' ),
		'view_item'                  => __( 'View Pixie Article Audience', 'pixie-article' ),
		'update_item'                => __( 'Update Pixie Article Audience', 'pixie-article' ),
		'add_new_item'               => __( 'Add New Pixie Article Audience', 'pixie-article' ),
		'new_item_name'              => __( 'New Pixie Article Audience', 'pixie-article' ),
		'separate_items_with_commas' => __( 'Separate Pixie Article Audiences with commas', 'pixie-article' ),
		'add_or_remove_items'        => __( 'Add or remove Pixie Article Audiences', 'pixie-article' ),
		'choose_from_most_used'      => __( 'Choose from most used Pixie Article Audiences', 'pixie-article' ),
		'add_new'                    => _x( 'Add New', 'Pixie Article Audience', 'pixie-article' ),
		'not_found'                  => __( 'No pixie article audiences found', 'pixie-article' ),
	);
	$taxo_options = array(
		'labels'            => $taxo_labels,
		'public'            => true,
		'hierarchical'      => true,
		'show_admin_column' => true,
		'rewrite'           => array(
			'slug'       => 'pixie-articles',
			'with_front' => false,
		),
	);
	register_taxonomy(
		'pixie-article-audience',
		'pixie-article',
		$taxo_options
	);

	add_shortcode( 'pixie_articles', 'pixie_article_list' );
}

// Must use 'init' rather than earlier 'plugins_loaded' due to need to flush rewrite rules (white screen of death otherwise).
// Handled differently when using Extended CPTs and 'plugins_loaded' can be used in that case.
add_action( 'init', 'pixie_article_loaded' );

/**
 * Handler for pixie_articles shortcode to list all Pixie Article titles.
 *
 * @return string
 */
function pixie_article_list() {
	$output      = '';
	$posts_query = new WP_Query( 'post_type=pixie-article' );
	if ( $posts_query->have_posts() ) {
		$output .= '<div class="pixie-articles">';
		while ( $posts_query->have_posts() ) {
			$posts_query->the_post();
			$output .= the_title( '', '<br />' );
		}
		$output .= '</div>';
	}
	wp_reset_postdata();

	return $output;
}