Can ArcGIS Online or ArcGIS Enterprise Viewer accounts use ArcGIS Survey123 and ArcGIS Collector to collect data?

Answer

No, the Viewer user type is insufficient. At least an Editor user type with Data Editor role and the Field Apps bundle added on are necessary to fully utilize ArcGIS Survey123 and ArcGIS Collector for collecting data.

The Field Worker user type also contains the same privileges as the Viewer with the primary difference being the Field Worker user type includes the Field Apps bundle.