Is nostr viral? If so, what is its product hook?

https://sacks.substack.com/p/product-first

I'm trying to build something around small-to-medium sized groups to create a form of this virality. Another idea is to imitate paypal, which made it possible to "email money" by making it possible to "email nostr". I'm not exactly sure how that would work, but cross-posting to other platforms and protocols is our friend, if the value proposition can be communicated in that context.

Other ideas?