This request has been floating around since 2017 as far as I can see and rather than just adding a comment that this would be a good idea, I figured I'd start a New Idea in hopes that ESRI software engineers might notice this and add this functionality. Adobe Acrobat PDF is accessible everywhere and by essentially everyone, being able to share a 3D scene without having recipient needing specialized software to view it would be great.
This is a duplicate of Support Export of 3D PDF out of ArcGIS Pro .
While you are adding this functionality, why not add ability to read GeoPDFs as well, the entire USGS topo map collection is in GeoPDF format and cannot be loaded directly into ArcMap/ArcGIS Pro without converting the data to a GeoTIFF.
This is a duplicate of View GeoPDF Files in ArcMap which is Under Consideration for ArcGIS Pro.