ADVICE FOR ALL: HOW I GOT MY ITEM BACK QUICKLY
@emily thanks for asking whether I found a courier. I never did, and during that search I realized that I needed to get moving on a multiprong strategy. I think everyone can do this by putting your thinking cap on, so here we go:
Look for any friends traveling to and from Rome who could help you get it out of security. When you ask them about their travel plans, also ask them whether they know anyone who lives in Rome or is visiting, and whether they'd be willing to help out. Think Airbnb hosts, Uber/taxi drivers, etc. I actually had a lead on a friend of a friend who was there and headed back to the States shortly, but I missed the window. Shame on me.
If #1 above doesn't pan out, HERE IS WHAT WORKED FOR ME, and what you're going to do next. I'm using Delta as an example of an airline and how to work through their employees. If you used another airline, the process would be the same.
Sit quietly for a few minutes and think of a few friends or family who have large personal networks. You know . . . the people who seem to know EVERYONE! They're going to help you network your way to your item. Tell them about the mountain you need to move to get your item out of Rome. Chances are, somebody you know knows a Delta employee. ANY Delta employee will do for the moment. I don't know the ins and outs of Delta's internal communications platform (email / other), but the employees have ways to communicate internally, just like every other company. If your well-connected friend can get a message to the employee they know, they can ask that person to see if they can identify any of their colleagues who are based in Rome or who may have travel plans there. You know what I mean. You'll need them to use their connections within the company to see if someone can get it out and "pony express" it back to you.
Be sure you include a meaningful incentive! For my friend's cousin, who works for Delta and initiated the internal networking process to find someone who could help me, I made a contribution to her favorite charity. For the flight attendant who was based out of Rome and made it his personal mission to get my item back to me, I drove to Atlanta to thank him and gave him a gift bag of snacks that he could eat on his flight home.
You will need to turn over a ton of your personal info to a relative stranger to get your item out of security. Have all of that ready to go - see the list of identifying info, inventory, etc., that security sent if you got notification from them that they have your item. Whoever grabs your item will need to get to the security office within the timeframes that they are open, so there's a fairly small window for them to pick it up if they're hustling to and from work. Importantly, they will also need to go through customs to get your item back to the States, so allow time for that, too.
Everyone can and should try this method, because nobody is finding couriers, and you have nothing to lose. It may take some cash incentives to get this done, but believe me, it was worth every cent to me to help others who were willing to help me. I'll never know how many employees were involved in reaching the man who brought it back to me. In the end, I got to meet the most incredible stranger who got my bag out of security and flew it to the states (he was the purser in first class and apparently frequently does this as a personal hobby/mission), and that was almost more exciting than getting my possessions back! I don't cry much, but his act of kindness brought me to tears. I was stunned at how far Delta employees are willing to go above and beyond their jobs to help passengers. I guess why they're so successful as an airline.
I hope this helps @Emily and others here who just need ideas for getting around the courier system. Best of luck to each of you!