Look at ReactOS, it's a GPL reimplementation of old MS Windows API and intends to be binary compatible with drivers and apps etc. written/compiled for MS Windows. I don't believe that a user trying to run some proprietary app on ReactOS makes that app become GPL. You can also have proprietary software on Linux.
If you would include OpenPCI GPL in AROS and non-GPL programs using the openpci.library it becomes very hard to argue these programs should not be GPL.