I have been adding blossom support to chorus.  It is almost done.  Branch is on github 'blossom'.

It supports GET/HEAD/DELETE for /<sha256>
It supports HEAD/PUT for /upload
It does not support /list or /mirror yet.
It does not remember or deal in content types (these are just blobs, I dont know what they are).
It requires authentication to upload or delete, but not to download.
It handles HEAD and OPTIONS and CORS stuff quite well.
It explains all the error conditions in detail in the X-Reason header.
It does not do other nice HTTP things like etag or cache stuff yet.
It uses async streaming and efficiently hashes and counts bytes as it goes.
It probably has a few bugs or omissions still.
It is optional and disabled by default.

After some testing I'll add blossom support to gossip so you can attach files to notes and it will upload and put the link in your note.