Diverting a massive amount of resources to devices where we can never provide decent updates and our core security features doesn't interest us. It would reduce the privacy, security, usability, app compatibility and robustness of GrapheneOS for users on the officially supported devices. It would also result in many people getting insecure devices. Many people would get those devices and then realize they made a poor decision later. We already see this happen with devices approaching end-of-life and already have to put significant work into avoiding people getting those.