Lack of standardization. Given that the project is still early, I understand things are due to change, but there are no standards for how things like the key rings should work or how the homeservers should work or interoperate. It just feels very centralized in a sense because I wouldn't be able to make my own implementations without having to copy straight from Pubky Core, and I figure that will have breaking changes. Whereas, with nostr, if I wanted to make some signer implementation, I can just look at the NIP. But maybe I'm missing something.

Pubky feels like an idea (a good one at that!) with a series of scripts, not the basis of a new protocol or internet.

There is no ecosystem, I would presume from lack of usage and lack of standardization. Maybe standardization will come in the future, but I didn't see anything on their website detailing anything of the sort.

One of the strengths of Nostr is its endless interoperability. Yeah, it's kinda jank sometimes, but it's beautiful that every client just Works (to some extent) with each other. Everything contributes to everything else. Standardization can also be a pain because if you make a shit standard that everyone uses, then you'll need to accommodate with backwards compatibility and such.

Please let me know your thoughts!