Let's be honest.... GrapheneOS sucks the big one
GitHub - RealityNet/iOS-Forensics-References: A curated list of iOS Forensics References, organized by folder with specific references
Диагностика и устранение ошибок iPhone на основе анализа логов Panic-full
As I know some use Google pixel hardware because bootloader can be unlocked and then locked again (for security reason) with custom rom. Read that One+ allow do the same. With other vendors you can only unlock bootloader if vendor allow.