If a file in the temporary folder was not completely uploaded it is probably be useless unless it’s a dlist file.
The dlist is the last file to be uploaded, as the backup is completing, because that’s when Duplicati knows how every file (and file chunk) of that backup will look. It describes what files are in this restore point and how to put the chunks together.
Sadly without this list those chunks are essentially just unnamed pieces that can be very difficult to piece together.
On repeated backups many files may be in previous file lists, but again any new files or changes would be “undocumented” without the new file list.
On a purely practical level, if it’s small files - or large chunk sizes - it is possible to look at the content of these chunks manually and put it together. For example You could easily recover the content of small text files that each fits within one or a couple of 50MB chunks, but you wouldn’t know the file name unless you had that info elsewhere. And of course this gets very tricky if it’s very large files or too many files for a human to deal with…