Pubky core is like Nip01, it is like DNS and WebDav, and it is more or less what I just described.

Now you can build on top of such stack, I am sure you could come up with 100s of micro apps ideas. Others will too. Your data (the public parts) will be available to them and theirs to you. If you also want every developer to interop with others, get them in a room I guess. Pubky core is not any more responsible for that than the spec of Websocket is responsible for Nostr clients understanding each other.

There is no magic for interoperability, and I don't personally consider it my mission, I want censorship resistant DNS, and a data store with an open API. Higher level abstractions will churn like hell, but at least the data will be there for anyone motivated enough to reverse engineer it and squeeze some value from it.