There are big tradeoffs being made here, so I wouldn't diminish those, but you can back up the private key stored on Yubikey.
The Yubikey isn't a signing device. It's a storage device.
maybe you can recover from a backup file
but you can't deterministically rebuild from a seed phrase
yubikey can also be used to sign ssh, fido2, webauthn, pgp etc
edit - I see it is indeed a storage (not signing) device in this context
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