Galaxy Watch 4 is the first smartwatch from Samsung to abandon Tizen to return to Wear OS, a step also dictated by the proximity between the Korean company and Google who have worked closely together to create an operating system for wearables that went fishing the best of both worlds, namely the same Tizen and previous versions of Wear OS.
However, it seems that this transition phase is not yet complete and that the debut of Wear OS 3, at least on Samsung smartwatches, has not been accompanied by the inclusion of all the typical features of the OS, such as full support for notification of two-factor authentication of the Google account.
Starting from 2016, all Wear OS smartwatches are able to provide consent for access to the account directly from the wrist, without having to go to use the connected smartphone. On the new Galaxy Watch 4, however, the message shown is exactly what was also found on the Tizen devices, or a notification that invites us to continue the operation from the phone, despite the device is now equipped with the Google operating system.
It, therefore, seems that there is still some way to go to complete the integration of the new smartwatches within the Google ecosystem.