> Can we use Workforce or Tracker with named users from ArcGIS Hub Premium?
ArcGIS Hub Premium includes two ArcGIS Online organizations.
(see how it works section)
You can certainly use Workforce for ArcGIS with the ArcGIS Online organization(s). Currently, Tracker for ArcGIS is only supported with ArcGIS Enterprise - but it should be available with the forthcoming ArcGIS Online Dec 2019 update.
Hope this helps,