Crear un endpoint REST personalizado en Magento 2

<?xml version="1.0"?>
<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Webapi:etc/webapi.xsd">
    <route url="/V1/gdw/health" method="GET">
        <service class="GDW\Hello\Api\HealthInterface" method="getStatus"/>
        <resources>
            <resource ref="anonymous"/>
        </resources>
    </route>
</routes>

<?php
namespace GDW\Hello\Api;

interface HealthInterface
{
    public function getStatus(): array;
}

<?php
namespace GDW\Hello\Model;

use GDW\Hello\Api\HealthInterface;

class Health implements HealthInterface
{
    public function getStatus(): array
    {
        return ['status' => 'ok', 'module' => 'GDW_Hello'];
    }
}

<preference for="GDW\Hello\Api\HealthInterface" type="GDW\Hello\Model\Health"/>