Custom Hook - Insert GeneratePress Element at Top or Bottom of Menu.php

// Add a GeneratePress Element at the TOP or BOTTOM of the Primary menu.
// generate_top_of_primary_menu
// generate_bottom_of_primary_menu
add_shortcode('top_of_primary_menu_hook', function($atts) {
	ob_start();
	$atts = shortcode_atts(array(
		'hook_name' => 'top of menu'
	), $atts, 'top_of_primary_menu_hook');
	do_action($atts['hook_name']);
	return ob_get_clean();
});

add_shortcode('bottom_of_primary_menu_hook', function($atts) {
	ob_start();
	$atts = shortcode_atts(array(
		'hook_name' => 'bottom of menu'
	), $atts, 'bottom_of_primary_menu_hook');
	do_action($atts['hook_name']);
	return ob_get_clean();
});

add_filter('wp_nav_menu_items', 'prefix_add_hooks_to_menu', 15, 2);
function prefix_add_hooks_to_menu($items, $args) {
	if ($args->theme_location != 'primary') {
		return $items;
	}

	// Add hook at the top of the menu
	$items = '<li class="menu-item custom-menu-item-top">' . do_shortcode('[top_of_primary_menu_hook hook_name="generate_top_of_primary_menu"]') . '</li>' . $items;

	// Add hook at the bottom of the menu
	$items .= '<li class="menu-item custom-menu-item-bottom">' . do_shortcode('[bottom_of_primary_menu_hook hook_name="generate_bottom_of_primary_menu"]') . '</li>';

	return $items;
}