Both .ows and .ova files come from a software called Web Studio and both are used for some kind of project purpose. This means that if any export is even possible, it would be done with the original software only, as projects are typically exclusive to the software used to make and save them.
The software was discontinued years ago, so if you are looking for a way to recover the content, perhaps you can still find old installation packages somewhere on the Internet.
Updated: October 13, 2023