According to the implementation spotted by Techtsp (https://www.techtsp.com/2023/08/web-environment-integrity-android-webview.html), currently Android is the only platform supported for WEI. The implementation defines two classes—AndroidEnvironmentIntegrityService and AndroidEnvironmentIntegrityDataManager—responsible for handling the necessary identifiers for WEI. Designed to store key-pair identifiers "Environment Integrity Handles" (read attestations), along with calls to the Play Integrity Attester for Android.
The AndroidEnvironmentIntegrityService class includes methods for creating an instance of the service and retrieving the attestations. On the other hand, the AndroidEnvironmentIntegrityDataManager class interfaces with the storage system to manage these attestations.