[crotchfire]

Why not buy a TKey Unlocked instead? https://tillitis.se/products/tkey-unlocked/

Then you not only have access to the device secret, you can even choose it yourself.

[cobratbq]

That's fine. It is indeed possible to perform a check for genuine hardware. (I'm not sure it qualifies as "attestation".) It does not protect you from malicious program-binaries and swapped devices.

[crotchfire]

Protecting against "swapped devices" is simple: put a secret key in the device, ask it to produce a signature, check it with the public key. Any device other than yours won't know the secret key.

I'm not sure what attacks you refer to when you say "malicious program-binaries". I'm having trouble imagining something fitting this description which is thwarted by the vendor blowing the programming fuse but isn't thwarted by you blowing the fuse yourself.