dinner? idk

I think kind 0 profile data at least?

But that's not really apps talking to each other, that's more like referencing the same thing.

he didnt mean that literally, nostr clients talk to relays and relays talk back to clients. interoperability is actually achieved when the data back and forth with relays can be created/interacted with from different types of clients, each specialized in different nips

I'm not sure how that's any different to 100 other things out there. Nostr NIPs are one big brainstorming whiteboard. Anyone can write a NIP, there is no real system to review NIPs (besides one person merging or not merging), and most NIPs are pretty general, like laws in sketchy places that can be interpreted however the court likes. Many situations where two clients use the same NIP but you cannot say their things are interoperable, A won't show Bs other emoji, B doesn't do tags that A needs to organise, etc. Interop is hard, you need to enforce an extreme almost diabolical level of detail, and have a way to be clear who is and isn't meeting the bar. What I see is basically each of these wildly different apps with their potentially wildly different interpretation of even the same NIPs (but usually different NIPs, and often one-off NIPs) using relays as a sort of decentralised public storage. If there was some system to facilitate interop that can scale in the real world then I'd be with you, but NIPs is not that.