How to download a file stored as a compressed BLOB

I have a BLOB column in my table which contains compressed files (using UTL_COMPRESS.LZ_COMPRESS).  I want to be able to add a download link to a report listing all the files, which gives access to the uncompressed file when clicked so that it can be saved locally.

I have followed various documentation / tutorials for declaratively downloading BLOBs, but it does not appear to support anything other than downloading the raw (compressed) BLOB itself.  I essentially want to inject a call to UTL_COMPRESS.LZ_UNCOMPRESS() somewhere, but I don't seem to be able to find any way to do it.