Thanks for the tip! While it looks like a cool feature, I don't want to give you false hope. As far as I can tell, the viewer integrated in pgAdmin4 is implemented using wxWidgets and it is therefore not directly integratabtle in DbVisualizer. We would therefore need more requests for this before spending time looking into it in more detail.
I just found out that the new version of pgAdmin4 will come with a geometry viewer (see link below). Working with GIS applications (PostGIS), that feature would be really handy. Perhaps not a core feature of a general db management tool, but maybe as an extension or plugin?