Are there any online community investigations of PhD thesis plagiarism outside Germany?
I am not aware of initiatives in other countries. However, while VroniPlag started out with examinations of German doctoral theses, it is no longer limited to those. Today, it investigates suspected plagiarism in PhD theses written in Spain, Ireland, Denmark, the Czech Republic, Austria, and Italy. To the extent that this is a continuing trend, VroniPlag already is an international project.

So the answer to the question in your title (which differs from that in the body), whether online community investigations of PhD thesis plagiarism outside Germany exist, is yes.