This is true for https://git.fiatjaf.com/promenade, but there is a way to generate an nsec in a distributed manner such that no one ever sees it (well, the signers can collude and recreate it). Search for Frost DKG (Distributed Key Generation) and there is a bunch of material and discussion I didn't read myself.
Discussion
It's also possible to do this with Musig2. I believe it is even simpler, each signer just needs to generate an nsec and they don't even have to do any dances to generate the combined npub, it's stateless and deterministic (they do have to do a dance potentially with the help of a coordinator for creating a signature), but it can't be m-of-n, has to be m-of-m.
Thanks, good to know!
But even if nsec isn't visible ever, I guess the question was about transferring "ownership" of it - that doesn't seem possible.
Why not?
Suppose you create this key on behalf of Michael Jordan that is invisible and all that you have is a secret code that gives you access to the bunker. There is a 3-of-3 multisig quorum that basically controls this key identity but you operate it. And you start mirroring Michael Jordan material in this profile.
2 years later when Michael Jordan decides to join Nostr, he talks to the 3 signers and proves that he is himself (by publishing on other authoritative social media) and the 3 signers revoke your access and give the real Michael Jordan access, they can also just give him the key shard material directly and he can then assemble the private key himself locally.
Of course this gives these 3 entities access to Michael Jordan's key forever, but we're assuming they're independent and won't collude.
