fiatjaf on Nostr: Is it possible to take an nsec you already have and split it into 3 somehow, give one ...

Is it possible to take an nsec you already have and split it into 3 somehow, give one shard to each server and then they somehow collaborate to make a signature? I think you can't do MuSig2 for that, but maybe some other, simpler (less safe?) algorithm? I've asked waxwing (npub1vad…nuu7) this once but he never answered.