You still can't exfiltrate the key material.
> If it's to protect against physical theft of the keys, they'll just put the entire Raspberry Pi in their pocket.
Just because someone has compromised your device doesn't mean they have physical access. That's the point.
> They're generating the private key on disk then importing into the YubiKey. Which defeats having an external key storage device because you have left traces of the key on disk.
The traces don't have to be left behind. Is this excessive 'overkill', or is the 'digital duct taping the windows and doors' insufficient?
> An instance of openssl or xca covers 99.9% of "homelab" use cases
The interesting thing about this article is that it adds a few 9's that are covered, and it's both easy and cheap.