Uploading in chunks could definitely solve the issue, and the OCI Distribution Specification does actually have some language about an optional chunked push API[0].

Unfortunately very few of the registry clients actually support this, critically containerd does not[1], so this means your regular `docker push` and a whole lot of ecosystem tooling does not work.

This also means that the single PUT must be able to support very large pushes as a single request, possibly even larger than what R2 or S3 would allow without using multipart upload. This means you actually need a server to accept the PUT, then do its own chunked upload to object storage or otherwise stage the content before it's finally saved in object storage.

This rules out presigned URLs for push too, since the PUT request made to the presigned URL can be too large for the backing object storage to accept.

There's also other processing that ideally happens on push (like hash digest verification of the pushed layer) that mean a server somewhere needs to be involved.

[0] https://github.com/opencontainers/distribution-spec/blob/mai...

[1] https://github.com/containerd/containerd/blob/192679b05917b5...