Hey guys, I fixed it! I finally got the part (from Hong Kong - may they have courage and persistence, the brave souls) and replaced the bent derailleur hanger with the new one. I didn't detach the cable from the derailleur during the operation, which made things somewhat unpleasant, but I had my son help as a third hand.
After playing a bit with the cable tension, I have the machine working perfectly, except the switching seems slower than before. We can reach all speeds, including 1 and 8, just the response to the click-shifter seems delayed somewhat. Still, I'm over the moon that I managed to repair this derailleur issue.
Thanks all for your help!