It seems possible today. Just a matter of spreading the vision. I think I saw someone a long time ago use Nostr in this way with a signing device btw. Your address book would be associated with your keys, so the signing device would have it all. + the public terminal can include its own “yellow pages” for businesses and people in the area. This is the selling point of using Nostr for DMs btw. It’s not that it has the most advanced privacy. It’s the potential ease and ubiquity