Add page models automatically in Kirby 3

index.php

<?php

use Kirby\Cms\App as Kirby;
use Kirby\Cms\Page;
use Kirby\Toolkit\A;

class DefaultPage extends Page
{
    //
}

Kirby::plugin('domain/plugin', [
    'hooks' => [
        'system.loadPlugins:after' => function () {
            $kirby  = kirby();
            $models = $kirby->extensions('pageModels');
            $pages  = A::pluck(site()->blueprints(), 'name');

            // Patch pages that don't use a custom page model
            $keys = array_filter($pages, function ($key) use ($models) {
                return array_key_exists($key, $models) === false;
            });

            $kirby->extend([
                'pageModels' => array_fill_keys($keys, DefaultPage::class),
            ]);
        }
    ]
]);