I'm not a fan of storing media on relays personally (some apps like 0xChat do it with images anyway, it’s very odd), but if we were going to do it, a dedicated Storage Relay designed to store a single Kind for these shards would make the most sense to me, regular relays should not store files, checksums yes, but not files.

Another problem is the highly excessive overhead you’d get from validation, every event has a signature, every event needs verifying, it’s much cheaper to download an image from Blossom (from a single signed event pointing to it) than to REQ + download + verify + coalesce potentially hundreds, maybe thousands of Shards (events) for a single file, battery and speed killer, those signatures would take up a relatively substantial amount of storage, you’d use more bandwidth than with Blossom.