Gamification is an interesting approach, but it would make the flow longer, and I don't know if is the correct approach for an onboarding tool, maybe it's a job for a client.
he.net did a VERY good onboarding for IPv6: https://ipv6.he.net/certification/
A Nostr onboarding could learn a lot from their approach. It is disguised as a "certification". They do provide a "certificate" at the end (customized image), but the point is that the "test" is the lesson.
E.g. first test is "prove you have IPv6 connectivity". For Nostr, it would be "prove you have Nostr connectivity" - by posting a note with a token.
Discussion
Which persona did you create your onboarding flow for nostr:npub10000003zmk89narqpczy4ff6rnuht2wu05na7kpnh3mak7z2tqzsv8vwqk?
What are their motivations, and jobs-to-be-done?