Is there a way to show only instances of a selected feature type in the Map view?
Not at the moment but you have a couple of workarounds.
You can set a property that does not actually contain a geometry as default geometry in the Schema Explorer. The default geometry can be changed by right-clicking on the desired property.
It is also possible to use the
Edit Style in the feature type context menu to hide the feature type
by setting its opacity to 0.