[mxscho]

Technically, you are free to implement the Exposure Notification [1] API for your own potentially open-source alternative of Google Play Services, right? Or why would this currently not be possible?

[1] https://en.wikipedia.org/wiki/Exposure_Notification

[johannes1234321]

People are working on that: https://github.com/corona-warn-app/cwa-app-android/issues/75

Edit: and also see https://github.com/theScrabi/CoraLibre-android-sdk/