The only way cloud gaming services will be available on iOS is through web apps. And so, the likes of NVIDIA, Microsoft, and Google will be complying with Apple's rules. After NVIDIA released its beta web app version of GeForce Now, Google Stadia is next. The company announced on the first anniversary of the service that it would be building a progressive web app version of Stadia that will run on Safari, with public testing happening in the coming weeks.
While Microsoft was the first to announce that it would be bringing its xCloud service to iOS via the same means, the platform won't be arriving until next year.
Source: The Verge