As you pointed out the use of the device name is associated with the legacy authentication endpoints that would allow to explicitly specify them. In the non-legacy endpoints that capability is not available, however, due to the fact that both legacy and non-legacy endpoints need to co-exist until the deprecated functionality is removed what you see currently is that there is some information automatically used in order to still display some information. Having said that I confirmed that if you’re using the non-legacy endpoints trying to leverage anything that’s associated with the device name functionality is not recommended.
In conclusion, device is a remnant of legacy authentication endpoints and should only be used if you still haven’t migrated from those legacy endpoints.