I hadn't seen those threads ….
Are you sure the dragon ate the penny ? was it seen to do so ?
At the very least , an xray will tell you for sure it's it actually eaten the coin.
An Australian penny (pre 1966) was 32 mm diameter - hence my alarm, the US penny is 19.05 mm diameter ). I had to look this up , .
Was hoping the vet may be able to use a rare-earth magnet on a probe to acquire the coin (coins like pennies have magnetic properties) or maybe an mini grabber slipped down the dragon's throat into it's stomach while it's under a general to simply remove the penny without needing to use a scalpel.
Much the same approach as using a crop/feeding needle would be involved , only the result is something comes out sticking magnetically to the end of the probe rather than something being deposited in the stomach.
I saw this every approach used on puppy who had swallowed something it shouldn't have (a key ring with some keys attached) on that british SUPERVET show (puppy was none the worse for the short period under a general and sent home a few hours later to it's very happy family.
An example of this done on child is here
https://www.scmp.com/news/china/society/article/2119192/how-chinese-doctor-found-creative-way-remove-magnets-boys-stomach
Of cause every vet surgery will have Hartmann alligator forceps , and a skillful vet should be able to use these to remove a coin from the dragon's stomach if it's under a general and he's using active xrays to image what's going on (with out having to actually cut open the dragon and stomach with a scalpel).
At the very least , an xray will tell you for sure it's it actually eaten the coin.