That's the part I'm missing. It's not only about deriving the keys but about a NIP that enables the issuing and revokal flow for a seamless experience of other users.

Is this possible already?

Surely you can generate keys from keys, so I can have a private key that controls multiple private keys.

Then I'd have an air-gapped store of all if my identities online, from which I can derived them again if I lose any particular private key, if I know the derivation path for constructing these private keys?