An indication that a technology is established is the availability of publications.
Are there any technical books about Nostr from the well-known publisher e.g. O'Reilly, Manning etc. in the works?
Or some books about the impact of this technology on economics and freedom published by Konsensus.network?
Mastering Bitcoin first edition was published in 2014 five years after the inception of Bitcoin.
Will Nostr beat that number?