Because OXPS format is scarcely supported and can be opened mostly only using the default XPS Viewer from Windows 8/10, you may want to convert it to standard XPS format which has somewhat better support in 3rd party programs.
You can do this for example with Microsoft's command-line program called XpsConverter which works in Windows 7 and higher.
The syntax for conversion of an .oxps file to .xps file would be:
XpsConverter /XPS /InputFile=sample.oxps /OutputFile=sample.xps
However, it may be possible that eventually more such tools with more user friendly GUI appear, because the XPS/OXPS format frustrates many users.
Updated: April 13, 2017