UPDATE
Wanted to follow up on this, as it's now become laughably absurd. The whole bike industry and its supply chain has ground to a complete halt, and my bike has the drivetrain equivalent of a 80's Lamborghini motor in terms of serviceability.
The bike shop (where I bought my new gravel bike) said sure, no problem, we can fix the busted rear derailleur piece on your road bike. I dropped it off there almost two weeks ago and never heard anything back, so I called them. They finally gave me the answer that no, they cannot fix it, it cannot be fixed by a shop. I was like, uh, thanks for letting me know, jerks.
The issue is that the busted piece is held on by a ring that is press-fit onto a bolt at the factory with some sort of hydraulic press. Not sure how you remove the ring without destroying the bolt. It's a ridiculously bad design. The earlier designs used a simple removable circlip. The shop said I might be able to send it back to Campagnolo USA and they could do it. I've called and emailed Campy USA but haven't heard back from them. Sounds like they don't want to deal with it.
I'm willing to buy a new derailleur unit and replace the whole thing, I could do that myself, but there are none available anywhere. Zero. I'm also willing to replace the front and rear ones to upgrade to a later generation, but that requires replacing the shifters/brake levers as well. I'd do that, but there are none available either. Only parts that seem to be possibly available are the top-of-the-line absurdly overpriced Super Record versions. Those would cost about $3K. I'm not putting $3K of parts on a seven-year-old bike worth maybe $2K in working condition. Better option is to buy a new bike and strip the usable parts off the old one for sale on Ebay.
So, I'm now shopping for a new bike. Problem is, complete new bikes are almost impossible to find. I can buy a bare frameset, but I'm not sure I can find the parts to make a complete bike. I'm looking now, and if I can even find them, I'll be ordering from like five different vendors. What a ****show.
I contacted one of the biggest dealers on the west coast, a place called Wrench Science, and they told me they have zero bikes in inventory. A bike shop with no bikes. They said they are taking orders for next season. As in, pay now, you might get a new bike next April. Ridiculous.