IMO For a stamp to be called a crypto stamp the pub and priv keys should be on the stamp itself so when it is mailed the keys are mailed in the stamp.
Quite dificult when u pay with web3 wallet ie NFt is tranfered right to your ETH adress while the physical stamp is mailed later.
Market as of today do not match your definition. Who's wrong?
I am referring to a Stamp loaded with a cryptocurrency such as Bitcoin.
To me the definition of a physical Crypto stamp is that the keys are on the stamp itself not the selvage.
TO give you an example...physical coins have the private keys loaded under the hologram and that one coin is enough to redeem you crypto, be it Bitcoin, ethereum or Litecoin.
I have even made coins with all in them, bitcoin and and NFT on polygon. Again its all in that coin, does not come with a second piece that is needed to redeem either. Just my two satoshi!
Then again, I was the first to come up with the concept of a crypto or physical Bitcoin stamp back in 2017...so what do I know right?