in the present is not possible to add a custom view with QoS metrics when we are on an interface context (we can only add such KPIs when we are in a device context).
In the present the views that give us some QoS metrics in an interface context are very limited in terms of number. These QoS KPI's are also only available on views out of the box and not editable. (present in "CBQoS" tab in)
There should be custom and dynamic views (similar to IM On-Demand/Multi-Metric Trend, for example) that would allow us to add QoS metrics in an Interface context in DX PM.
This would allow the network operation teams to have greater visibilitty on which QoS are configured in the interfaces and allows them to troubleshoot and manage QoS related issues more quickly.