At a technical level, the IUX slot is an extension panel in the browser
subapp. The panel allows you to configure a list of extension views in
the workbench - see
extensionViews for configuration and properties.
Any view implementing UiFrameworkView could be inserted into the slot.
You can create a view for displaying data that would benefit from value
context and can switch data whenever the selected item changes. The
following is an example view for displaying page titles, with
valueContext.observe triggering an update whenever selection changes.