

They are usually just .pkpass files, so any app that can show them should work. Most likely the “Hinzufügen zu Google Wallet” link will also work since it just links to the pkpass file. But be prepared to get asked if it is a screenshot a lot. I am using passandroid (further down this thread) and it works.
Sorry i dont follow? Google Wallet also supports pkpass files and i doubt that they use anything else. That would be so much harder for no gain.