The idea behind keyoxide, keybase, etc is that you post signed proofs that you are in control of various accounts online (twitter, Reddit, web, etc). Normally you would use pgp but you could use nostr signatures instead.

If these proofs were stored in notes on nostr, nostr clients could verify these proofs and say for certain that said nostr pubkey controls said accounts on the internet. This would be much more powerful and reliable than nip05. This would be true verification. And it would be the most decentralized version of keybase/keyoxide since it would be stored in nostr notes replicated across multiple relays. nostr:note1275rd6v83g8877y0ftxh79jqpnp3ptpcz8f24gav3njlu8n2jjtqecfvs3