“The new Android WebView Media Integrity API will give embedded media providers access to a tailored integrity response that contains a device and app integrity verdict so that they can ensure their streams are running in a safe and trusted environment”
Google says Web Environment Integrity “is no longer being considered by the Chrome team.” In the same post it pilots the same idea for Android WebViews. The verdict only works on devices with Google Mobile Services, so a de-Googled phone fails by design. Google dropped attestation from the browser and moved it somewhere with less scrutiny.