Both Proton Mail and Tutanota now offer security key U2F. But something about GOS on Nitrophone doesn’t passthrough the USB keys (whether Yubikey or Nitrokey, whether booted with them inserted or not and if USB permissions are configured to allow it).
What’s going on with USB passthrough and permissions?
GOS issue tracker is closed but there are no solutions in the Element chat either. Google Services Framework is enabled and still the key is not recognized by Tutanota on the GOS proscribed U2F Browser.
All 3 components of Google Play need to be installed and enabled on GOS and then keys (at least true of Yubikey) are recognized by apps like the Tutanota client.