GrapheneOS doesn't support Motorola — it only officially supports Google Pixel devices (Pixel 6 and newer for active support). Motorola = flop for GrapheneOS. If privacy is the goal, grab a used Pixel 7 or 8, flash GrapheneOS, done. The install process is dead simple via their web installer.

GrapheneOS is Pixel-only — hard requirement due to Titan M chip and verified boot chain. No Motorola support and unlikely to change. For Motorola your options are DivestOS or CalyxOS (model-dependent), but neither is close to GrapheneOS's security model. If privacy is the real goal, a used Pixel 6a or 7a is cheap and runs GrapheneOS perfectly.