Something like Rclone and a cron job, or else s3 mounted via FUSE, could possibly bridge that. Of course then you have to worry about reliability of the bridge...
I can understand why it'd be preferable to avoid such a bridge layer, and indeed I too would rather just have a transparent view of what's going on at the protocol level.
Stability and performance at scale sound like implementation specific properties though. If you've tried this, I'd be curious to known about the specific issues you encountered.