I noticed your next config doesn't allow for metadata & generateMetadata and you are right, the link you showed doesn't say anything about it. But metadata & generateMetadata are allowed to be exported according to https://nextjs.org/docs/app/getting-started/metadata-and-og-images#static-metadata and https://nextjs.org/docs/app/getting-started/metadata-and-og-images#generated-metadata. It doesn't even worth to offer my help to provide a PR it's a couple lines of code. I hope this helps.

...by the way generateViewport should also be allowed for nextjs (https://nextjs.org/docs/app/api-reference/functions/generate-viewport#generateviewport-function)