Universal 2nd Factor

 Universal 2nd Factor  (AKA U2F  ) is a standard for two-factor authentication using hardware tokens.

Specifications: https://fidoalliance.org/specs/fido-u2f-v1.2-ps-20170411/fido-u2f-overview-v1.2-ps-20170411.html

Browsers
Currently native in Chrome and Opera. Support in Firefox planned and currently existing using an addon (which hasn't been updated yet to a WebExtension).