Presigned URLs?

Is there a reason why this project doesn't use presigned S3 URLs (like with aws4fetch) to avoid the 500MB request body limit?

I see CNCF's Distribution Registry appears to do this. https://distribution.github.io/distribution/storage-drivers/s3/

No files, tests, or entry points are named. Start by tracing how uploads reach the Workers and R2, then compare that flow with CNCF Distribution's S3 storage-driver documentation and aws4fetch; done means agreeing on and implementing a presigned-upload design that avoids the 500MB request-body limit.

Written by the indexing model from the issue text.