https://github.com/googleapis/googleapis/blob/master/google/... is a more complete version of this. It supports resumable uploads, and the download can start from an offset within a file, allowing you to download only part of the file instead of the whole.
Another version of this is to use grpc to communicate the "metadata" of a download file, and then "side" load the file using a side channel with http (or some other light-weight copy methods). Gitlab uses this to transfer Git packfiles and serve git fetch requests iirc https://gitlab.com/gitlab-org/gitaly/-/blob/master/doc/sidec...
Another version of this is to use grpc to communicate the "metadata" of a download file, and then "side" load the file using a side channel with http (or some other light-weight copy methods). Gitlab uses this to transfer Git packfiles and serve git fetch requests iirc https://gitlab.com/gitlab-org/gitaly/-/blob/master/doc/sidec...