There are bits and pieces available for some remotes (like S3 example you gave) including local where rclone supports sparse files. But as I understand what is missing is unified "resumer" interface which could make resume operations possible where available - effectively different parts of rclone internals have to understand what "resume" is. There are multiple opened issues on github but so far only resulting with years long discussions:) Lack of it is not only painful for large transfers over poor internet connections but also in some cases creates unwanted garbage left behind. This is dark side of chunker for example:) Interrupted transfer can leave huge amount of invisible chunks and rclone has no mechanism to clean it. I even posted in Howto how to clean them manually.