nostr:nprofile1qqsgyrr4mde4yd6c0rn4cgz2tyr8sf8zsru5k7l8d52757zr9gdkufqtfq542 i'd start with a Nitrokey 3 if open source is the priority. and FIDO2 keys handle logins rather than transaction signing, so anything aimed at bitcoin wants a signing device instead.