kinda reminds me of this. Crypto bank notes...
https://honest.cash/v2/stickman/bitcoin-cash-symbinotes-physical-fungible-off-line-paper-based-bch-6675
people are trying, certainly. The fundamental problem is counterfeiting (physical attributes fail) A flaw of other 'cryptonotes' is reliance upon internet.
Now regimes blockade, censor, or simply disable the internet. In such places only 'paper' currency or 'barter' currency (Au,Ag,?) has value. We need a cash that needs no internet.
That means a piece of 'paper/plastic/ceramic' that physically cannot possibly be counterfeited. According to quantum mechanics such a beast could be fabricated.
As a matter of mathematical and physics, we already do exactly that whenever we cast a brick or print paper or ?: In a quantum perspective anything we create is utterly unique.
Yes, this gets weird in microseconds. Imagine for a moment you could buy a 'scrying stone' which would decrypt the quantum appearance of a coin reflecting a specific laser light.
A "coin" would have a specification written on it that, under a specific light, reflection would yield a specific pattern through a 'standard' 'scrying stone'. True Magick.