How do you update that open source code without network connectivity? How do you securely input long transaction data to sign?

> I think the answer is just have good security and dont get hacked.

So you proposed a way to be more secure, only to discard it yourself in favor of “just having good security”?

You don’t. It’s not networked. It doesn’t need updates.

In fact, updates are only a risk. You physically remove anything that can allow updates to happen + anything that allows wireless networking.

USB flash or QR code to transfer data

I agree my approach is not great, I dont own a lot