It doesn't make sense to have an airgapped signer as your main nostr signing key; it would be stupidly cumbersome just to like a post.

My demo branch in the above thread instead focused on #nip26 delegation. Your main key is protected via the airgapped signer, but you use it to authorize a delegate key to sign on your behalf for a limited time. That delegate key gets loaded as a hot key in your nostr apps. If it gets compromised, oh well, it'll eventually expire.