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.
I’m in an unsupported region so I’m afraid I can’t help much :(
In my case I just looked around a local eBay-like site and went with a reputable enough seller, fairly standard procedure there.