The “other one” mentioned is not really an invitation based onboarding tool.

nosta.me is really Nostr’s first dedicated onboarding client, but assumes that a person will just go there without any “real world” relation to somebody already on Nostr. It has no facility to discover existing WoT connections to a newly created account. Additionally, it has a pretty cumbersome and “in your face” key management UI, which I found off putting for inviting friends.