https://materialbitcoin.com/en/
It's funny because when, 8 or 9 years ago I saw them using cards with private keys in paralelni polis, I laughed at it.
Seriously though, wtf is wrong with people?
Discussion
The first version of hackerbadge just sent the private keys to the PoS device, and blind signed the transaction that sent the change back to the same address.
I loved the UX tho!
The dark side of good UX can be that you mislead people who are most attracted to it. A good example is the bullshit on that page about "hacker proof", "robotic process" and "isolated network facility".
Just listening rn to a podcast with a guy who lost 1.4btc, using these (although I have no idea if these cards were at fault, the fact that he was even using them is already tragic).
I went to a survivalist expo locally for fun, and I saw someone selling similar products. Just basically a pre-generated prviate key covered by a peel-off with the public information. I asked how I knew that the manufacturer didn't know my private key, and it was the same story: "A highly trusted isolated facility".
I personally am excited to receive all Bitcoin on-chain transactions to the same convenient address 🙄
Yeah, that's really bad. But the private key part is somehow infinitely worse!
It is a cool concept except for the part where your trust a 3rd party with your private key. I would if a guy could acid etch stainless steel at home and achieve a similar result?
In this case you are not trusting a 3rd party with your private key; they are trusting their private key with you.
What could go wrong?