See my post on the new batch API for NFTs in my post in the NFT working group. The intention is to align the APIs of both the ICRC-4 and NFT WGs.
- Option 1 (for completeness) has full batch semantics and a top-level batch error.
- Option 2 is a full batch API with a flat error structure and relying on ordering, i.e., not repeating the request elements in the response. Also, the response need not contain all request elements.
- Variation of Option 2 is a full batch API, not relying on ordered responses, but repeating the request for each response. That is the NFT analogon of your proposal above.