[lkbm]

From what I understand:

* FastMail has implemented WebAuth, the newer standard, which Firefox supports

* Google hasn't implemented WebAuth because they have to(?) wait for the end-of-life of old Android devices.

* Firefox is going to put an override so that you can use the old standard on Google accounts, which Google does support.

It sounds like Google's slowness to enable WebAuth is a somewhat legitimate issue of backwards compatibility for old devices, though I haven't personally evaluated it.

[chrismorgan]

FastMail is still using the old FIDO U2F API; we’ve been planning on migrating to WebAuthn since it was finalised, but investigation revealed that the migration would not be entirely straightforward (especially if tokens registered with WebAuthn needed to still work with U2F, which at the time was important but could probably now be skipped), so we deferred it, since the U2F support is adequate for most users. I expect this is the experience with many small teams that support the FIDO U2F API. Documentation on migration is difficult to come by; I think https://www.imperialviolet.org/2018/03/27/webauthn.html is the main source I’ve encountered.

[lkbm]

Thanks for the clarification.

[tgragnato]

Android devices do not receive updates. This creates all sort of issues, including inconsistency and lack of features. Legitimate and sensible decision, but sad.