I do want a good pgp/ssh compatible card with Curve225519 and can’t find one - yubikey has RSA and P384 iirc, but none have 25519.
(I need to sign data often; rsa 2048, the minimum rsa length acceptable at this point, is both slow on hardware elements and very long)
In August 2019: "the YubiKey now also supports ... Curve25519, the default curve used in ssh (EdDSA and Diffie-Hellman)", "Addition of Ed25519 signature support, a modern ECC curve".
See https://www.yubico.com/blog/whats-new-in-yubikey-firmware-5-...
Last I saw there were patches put forward to the devs since 2015 and they consistently refused to look at them, let alone merge them.
Note that the ed25519 is not as easy as it seems, ssh agent doesn’t support it yet. I wrote a couple notes/details in the somu campaign you linked, towards the end.