https://github.com/RupertBenWiser/Web-Environment-Integrity/blob/main/explainer.md
Implementations for Web Environment Integrity can vary from platform to platform. For example, on Android we must store key-pair identifiers called “handles” and make calls to the Play Integrity attester. On other platforms, the flow may be much different.
When adding WEI support for a platform, code that is specific to that platform should be placed in the appropriate platform-specific directory (e.g. /android). Code that can be used across platforms can be placed in a /common directory.
Currently Android is the only supported platform for WEI.