In fact, a verifiable credential issuer could issue a VC with a nostr npub within the subject (now that we have nostr DID schema in draft).
And W3C's Verifiable Presentations JSON can already be signed by a nostr nsec.
Nostr loves JSON after all and VC/VPs are ultimately just signed JSONs encoded in Base64.
Probably all these were lost in translation when presented on stage by non-devs.