Just my FAA number per the requirements. On my Mav I had my name but I think the requirements were different cuz back then you could put the info inside the battery compartment. Now, last I checked, the FAA # is supposed to be on the outside of the aircraft.
What got me thinking about it was a video I saw while perusing Skydio 2 videos on YT of a guy that got fined $5000 for his drone not being registered and marked. He said that was the end of his drone flying.
Well, I originally asked about just having something like a Ph# on the drone in case something wonky happened and you lost it. If found, you might get a call. But then you brought up the FAA and I commented on that.