This is super clever! Even now it's often easy to forget that physical, actual money (let alone the gold that it's supposed to represent or whatever) exists. I almost never touch money, and I wouldn't be surprised if we're a few generations away from this happening! You also did an awesome job of representing multiple factions that each want the coin for their own purposes, explaining their intentions, and then allowing them to play out alongside the PCs who end up with the coin itself.
- ✨Beth