TL;DR
- Efforts like Graphene OS face increasing pressure from apps that refuse to run on non-standard Android.
- The custom ROM project characterizes Google’s approach to device attestation as incomplete and flawed.
- Graphene OS is prepared to take legal action if Google won’t let it pass Play Integrity checks.
FTC act is the most useful against this sort of behavior and only the FTC can file suit for that, not individual companies. I don’t think this could be filed as a violation of the Sherman act. See here for an overview: https://www.ftc.gov/advice-guidance/competition-guidance/guide-antitrust-laws/antitrust-laws