GOS devs don’t let anyone incorporate their code.

False

They also refuse to provide basic functionality like inverted navbar buttons.

This is supported in AOSP now.

Because they’re diva devs.

This doesn’t seem like a mature thing to say just because you want to flip buttons and are annoyed that the privacy and security-focused project didn’t add a feature to flip buttons.

That’s very false. There are other OSes with GrapheneOS code or forks of GrapheneOS.

You don’t need to reinstall as many people have suggested. There are instructions on the website for this https://grapheneos.org/faq#preinstalled-devices. Basically, verify the installation and do a factory reset from Recovery.