So, now having a better visual of the coins in the chest, I notice on the "heads" side (assuming the "tails" side of the coin is where the Poke Ball logo is usually placed in the Pokemon World) that there's two distinguishable parts of the design:
- In the center is a hexagon, which is a shape that has been associated with Terastallizing, notably the gem on the headband of the crown (you know, the gem which has the pair of glaring eyes on it).
- Surrounding the hexagon is a what looks to be a laurel wreath. The laurel wreath is a symbol dating all the way back to ancient Greece, it was a symbol of Apollo and symbolized "victory". Thus it's a popular symbol for major competitions (usually as a frame rather then centerpiece), though in ancient times was also used for military victories.
So, a laurel wreath around a hexagon in this case could mean: (1) if these are meant to be taken as ancient coins than they could mean a victory was achieved via Terastallization and the coins were minted in their honor. Or (2) if these are modern day coins they could be something related to either the Paldean Pokemon League or another competition in Paldea (or possibly the Academy's Treasure Hunt) which involves Terastallizing Pokemon as its main focus, the coins minted as a token to be used in someway during it (such as participants of the competition are given a coin to show they are a part of it or a wanna-be competitor would have to get their hands on one so they can submit an entry into it).
I guess we also shouldn't avoid the "tails" side as it's not just the Poke Ball logo. It also has three dots above and below the logo and in the middle there are three connected loops. Altogether it kind of looks like a face not dissimilar from a Bronzor's (which also has a leaf symbol on its back):
Whether Bronzor will have anything to do with this we'll see soon enough. As or writing the chest has 959 coins in it, and each time there was a "9" it had a gold background, and with only 3 digits the max is going to be 999.
The chest itself isn't that noteworthy (though for some reason they gave us a view of the back) except for the seal. The seal looks similar to the loops in the middle of the coin's Tail side, though turned horizontal, the middle "loop" is now the bigger one, the two "loops" below and above are filled in solid, and at the top there's a bar it touches. Are these meant to be associated symbols? Different symbols that just so happen to share a similar shape? Am I looking too hard into this (this, probably this)?
EDIT: Okay, so while typing this a new update occured!
There's now a hidden "four" tab, clicking on it will show an animation of the chest's bottom and top half separating, held together by the backstrap. In addition, when clicking around, a strange noise which sounds like a Pokemon cry (along with a scatter of coins) will be heard (along with the screen going black for a second). Said cry doesn't sound like one we heard I don't think, definitely doesn't sound like a Bronzor.
So, the chest is possibly a Pokemon?
Also, Serebii has mentioned the creepy new Pokemon and ???? coins which Gold PokeStops have been giving were confirmed to become a lot rarer.