ArcGIS Pro 3.3.0
I have a .pitemx file from https://www.arcgis.com/home/item.html?id=0f2878b910954110b05c1aec9a07f1c7 > Open in ArcGIS Desktop > Open in ArcGIS Pro.
When I drag the file from File Explorer to ArcGIS Pro, I get an error:
Error - Add data
Failed to add data, unsupported data type.

I'm aware that I can double-click the file to open it in a new Pro session. But it would be more intuitive if I could also drag and drop the file to an existing Pro session, and not get an "unsupported data type" error (misleading).
Additionally, I can't seem to use the Open Project dialog to open the file:

It's confusing that double-clicking the file in File Explorer works, but the Open Project dialog doesn't work. I would have thought those two techniques would be similar.
Also, I can't seem to use Catalog to open the file either. The folder doesn't expand, so I can't see the file:

The Add Data dialog doesn't show the file either:

But maybe I'm missing something. I can't find much documentation on .pitemx files: