Interesting!
Some quick feedbacks:
- You could assume http(s), if the protocol is omitted;
- The path-code is not deterministic, so we end having a lot of different URLs pointing to the same resource, I don't know if this is a good thing;
About the name/payoff, I would use something like "xxxxxxxx, a URL shortner powered by nostr".
"NOSTR URL Shortener" may mistakenly suggest that the url refers to a nostr resource.
The name: zippp.it ?