Every message you send in nostr is signed with a private key. I’m assuming you’re not signing that much with your bitcoin seed.
Lightning keys are hot which is why you should only keep as much as you’re willing to lose in lightning.
Another reason is privacy. You don’t really want to associate your life savings with your social identity.
I know that ! My point is that you can generate your nsec offline and allow sign events like for few months. nostr:npub1tv8gmfhalwnxxquxjzeh6gtdsdz6vg7vx0s3rt7s7uuw6aujh32qn77wn2 had some sort of this idea using seedsigner back in the days
Unless I’m missing something, you can’t just “allow” sign events with the key offline. Maybe there’s some delegation protocol, but you need access to the nsec to sign every message. Signing can’t happen without access to the private key.
The closest we have is something like the VLS (validating lightning signer), which is a dedicated, internet enabled signing device that supports encoding permissions about limits on what the device will sign. Unfortunately it still falls victim to the problem that your private keys are still exposed to the internet.