You have made a quality post as

No matter how similar you think an NFT asset looks, they each have a unique identifier making it completely difficult to be interchangeable.

Even the duplicated copy won't be similar to original as for their digital Identity is concerned . You are right .

InterPlanetary File System (IPFS) is a distributed system to store and access files, data, etc, and has the full function of a centralized cloud.

It is a web based sexentralised communication protocol which enable secure storage , retrieval and sharing of files .you explained it well.

Good luck