...?
Although I'll concede that I'm now wondering what's preventing compromised hardware from faking this part too. A complex malware could even receive firmware updates, dump them in an unused partition, and report to the connected host that it promises that it's definitely running that firmware, right? Hmmm.
The only way around that would be for Trezor to ship their devices with some sort of attestation function (e.g. a private signing key to which they publish the public key, or sign it via a PKI and include a certificate) and validating that, not just the statement "I promise to be running the authentic firmware", a hash over the firmware, a complete firmware dump or anything else not involving a challenge-response or uncloneable function of some sort.
In that case the golden keys can leak, but it's better than nothing.
This is an absurd security model. Where's the root of trust here? How do I know I am initially talking to an authentic "blank" device, and not a malicious one pretending to be one?
> If unofficial firmware has been installed, your device will flash a warning sign on its screen upon being connected to a computer.
Hopefully, malicious firmware won't meddle with this feature in any way...
The vendor here is either completely clueless, or is trying to paint a better picture for prospective customers despite knowing better.