A simple router for WordPress REST API - Laravel-like

router.php

<?php
defined( 'ABSPATH' ) or die;

namespace Kevin;

class Router extends \WP_REST_Controller
{
    protected static $instance = null;
    public function getHandler($namespace, $endpoint, $callback) {
        \register_rest_route(
            $namespace,
            $endpoint,
            [
                'methods' => 'GET',
                'callback' => $callback,
                'permission_callback' => function() {
                    return \current_user_can('upload_files');
                },
            ]
        );
    }
    public function postHandler($namespace, $endpoint, $callback) {
        \register_rest_route(
            $namespace,
            $endpoint,
            [
                'methods' => 'POST',
                'callback' => $callback,
                'permission_callback' => function() {
                    return \current_user_can('upload_files');
                },
            ]
        );
    }

    public static function __callStatic($name, array $arguments) {
        $name = "{$name}Handler";
        if (is_null(self::$instance)) {
            self::$instance = new static();
        }
        $r = self::$instance;
        return $r->$name('your-rest-namespace/maybe-version-too', ...$arguments);
    }
}

routes.php

<?php

defined( 'ABSPATH' ) or die;

use Kevin\Router;

add_action('rest_api_init', function() {

    Router::post('/login', function($payload) {
        $KBSDResponse = wp_remote_post(
            "https://example.com/v1/login",
            ['headers' => []], // Maybe an auth header?
        );
        return new WP_REST_Response(
            json_decode(wp_remote_retrieve_body($KBSDResponse), true),
            wp_remote_retrieve_response_code($KBSDResponse)
        );
    });

    Router::get('/all', function($payload) {
        return new WP_REST_Response(); // etc etc
    });

    // You could also use a class and namespace it
    Router::get('/the-thing', [MyNamespace\ThingController::class, 'data']);
});