When GPG is your ssh agent, you can use RSA or ed25519 keys stored on a smartcard (like a Yubikey) to authenticate via SSH.
It's generally preferable to use a `-sk` key type, though, by which the remote server can essentially enforce that you're using a smartcard and not a normal keypair backed by a file.
It's generally preferable to use a `-sk` key type, though, by which the remote server can essentially enforce that you're using a smartcard and not a normal keypair backed by a file.