The real challenge with Nostr is largely surrounding it’s decentralised first mantra. Many problems solved in centralised ways, don’t apply for Nostr - it means starting from scratch. Proven computer science approaches literally don’t exist yet, or are early.

Limitless identities/accounts, fake likes/reposts, spam, recommendations, discovery, content filtering/personalisation, funding, media hosting/content hash addressing, etc.

Bitcoin largely solved a single, yet crazy important decentralisation problem. Many many more still remain. Nostr is both an Interface and foundation, where many more of these decentralisation challenges can develop robust approaches on. It’s not a golden egg with everything solved or perfect.