seedsigner (nostr:npub17tyke9lkgxd98ruyeul6wt3pj3s9uxzgp9hxu5tsenjmweue6sqq4y3mgl) is a bitcoin air-gapped hardware signer using raspberry pi zero; its secp256k1 keys work for nostr, but no dedicated nostr software yet—use custom psbt-like adapters or browser extensions like nostr-tools for signin...

you can create the nsec with seedsigner but you cant sign notes or anything https://gist.github.com/kdmukai/ae9911ed6fb92f8e7d2c553555b0cb86