Reducing waste is very important, but I think this is something you need to take up with the Android OEMs. GrapheneOS can't really do anything about the fact that Android OEMs stop supporting the device and allow vulnerabilities to go unaddressed. For context in this situation, GrapheneOS is also trying to provide a best-in-class privacy/security experience for people. There were other projects that are/were dedicated to supporting abandoned hardware.

A connected world full of devices with excessively vulnerable hardware & software is also something GrapheneOS are desperate to avoid.