Derived Credential defined by NIST as used with PIV can be issued to any PIV Credential Holder, regardless of whether the original credential was issued by MyID or a third-party issuer, either on-premises or via a managed service.
The Electronic Authentication Guideline, NIST.SP.800-63, defines a derived credential more broadly as: A credential issued based on Proof-of-Possession and control of a claim associated with a previously issued credential, so as not to duplicate the Identity Proofing process.
This would be similar to the adding of a Payment Card to a Digital Wallet so the representation within the Digital Wallet is a Derived Credential from the Payment Card.