With signal-cli and perhaps other third-party clients, you can register a new Signal account on an ordinary computer. You do need a phone to receive the Signal

With signal-cli and perhaps other third-party clients, you can register a new Signal account on an ordinary computer. You do need a phone to receive the Signal confirmation SMS, but that can even be a dumbphone. Obviously signal-cli is never going to be a solution for the mass public, but using it is an option for some HN readers – this is a "news for nerds" website.