Comment by gbraad

A while back I created a fallback for use from my dotfiles that can be used from the command line: https://github.com/gbraad-dotfiles/upstream/blob/02deb3ef922... using zsh, openssl and xxd

This is not the first attempt I made. That was about 11 years ago with https://github.com/gbraad-apps/gauth using JavaScript as an application that would work on a Nokia Symbian/Maemo phone and as a webapp.