I think there are two interesting ERC-721 extensions that could be proposed here - one that defines an interface for querying the address that burned a given ERC-721 token, and one for specifying the cross-application definition of canonical assets for an NFT held in it’s ERC-6551 address. The latter interface should probably include the details of the account holding it’s asses (which could be ERC-6551 specific or more general like an ERC-4626 vault or custom contract) in it’s return value. I would recommend separate proposals for each if considering submission of an EIP.