This should be SUPER easy as an update to the Experience Builder Image widget.
The use case is that you have an image you want to overlay on top of another widget, AND you do not want the image widget that is over the other widget to block using the widget underneath it.
In this example I have used the Tattered Map Sandwich approach ...
(https://www.esri.com/arcgis-blog/products/arcgis-pro/mapping/tattered-map-sandwich)
... to produce a dynamic map that looks kind like an old treasure or pirate map.
https://experience.arcgis.com/experience/9d849c1e005a4ac4b844d02d8fe0fa37
The problem is that the top layer image of the map sandwich blocks interaction with any layer below it, despite it being mostly transparent. So it appears you can use the map, but the mostly transparent overlay is in the way.
This can be fixed with a single CSS attribute "pointer-events" which can be set to "none" for any given element in an HTML document. If the Image widget, at least, had a way to toggle this CSS attribute on for specific elements we could have creative and artistic use of overlays that do not block content lower in the Z-order stack.
Other ideas might be to produce a military themed image-map-image sandwich to give the effect of looking at an old radar screen. Or to give effects of looking at a map through a window.
It could also be used to emphasize branding of an Experience with an overlay image that does not entirely cover the widgets below, but still might provide a large logo in one corner that you do not want to block clicking on widgets below.