There's an experimental compression remote, which I addmittedly have not experimented with at all.
I wonder if this could be combined with deduplication, for a transparently compressed/deduplicated backend.
I've used restic in the past, and really like how it deduplicates. I really wish I could use it's deduplication and compression as a normal remote. I've fuse mounted it and it feels seamless. The only drawback is that you are forced into using snapshots, so you fuse mount a snapshot at a time. It's also read-only.
I don't have the programming skills to do anything about this, but it seems like it could be useful to have a remote that would function similarly to restic with the deduplication, but without the snapshotting- just let me upload files there.