These are Android games from the Play Store, so even if Google shuts down this Windows support, they likely won't provide refunds because users will still have access to the games on Android devices. They offered refunds for Stadia purchases because the purchased games could not be played anywhere after they shut it down.
Yea it probably is just that. Best thing to do is install a modded version of Windows Subsystem for Android (WSA) with Play Store integration. Check the MustardChef github repo. Then use Mantis GamePad Pro for controller support for unsupported titles. That's what i use and have all the best apps and games the Store has to offer. Performance is good now that WSA has Vulkan support, but not perfect just yet for 3D intensive titles.