Technically speaking, after plenty of attention and pressure put on Apple, the company does allow for cloud-based streaming services to be used on its devices. However, it's not via the App Store, and it's not with an app via the App Store. Instead, services like Microsoft's Xbox Cloud Gaming, Google's Stadia, and Amazon's Luna are accessible via Safari. But it sounds like Apple's considered something else for its own service.
Apple has reportedly held internal discussions about launching a cloud gaming service