Some CLIs need to select individual fiducials from a list.

Currently, the node selector supports picking a fiducial list node. To select one fiducial via that method, you would need a single fiducial per list, or use the selected flags on individual fiducals (set via the Markups module GUI table), as the CLI module logic is set up to only pass selected fiducials.

There is a simple Markups widget that could be investigated for tweaks to support a list selector + selecting fiducials functionality.

Another option would be to create a new qMRMLFiducialNodeComboBox widget that allowed selecting a single fiducial list and providing check boxes next to each fiducial in the list to toggle the selected flag on them. Then add support to the CLI logic for this new widget. It would need to listen to some specific events on the fiducial list assuming it was just showing the name and the selected state for each point:
NthMarkupModifiedEvent,
MarkupAddedEvent,
MarkupRemovedEvent
as well as the standard MRML node combo box of listening for events related to the fiducial lists.
New events could be added specific to the selection toggles.