[I don't have an answer so I apologize if this just sounds like another 'me too' post]
However, I'm also reasonably familiar with the format so as to offer a few comments.
First off, I don't believe we'll ever see an iOS app that uses DSS files unless Olympus themselves comes out with one.
As you mentioned, the DSS (and .DS2 'DSS Pro') formats are specific to Olympus recorders. It is definitely a proprietary codec that was developed and owned by a group of 3 companies (including Olympus). I have never seen any app that could read/write DSS files that did not come from or was licensed by Olympus which leads me to believe that they keep very tight control over its use. I suspect there is enough of a licensing fee involved that prevents 3rd party apps from using it.
In have also never found any open source apps that knows how to read DSS files, any publicly available documentation on the format itself, nor any published attempts at reverse-engineering it. All of which reinforces my opinion that it will likely always remain a proprietary format.
Sorry for the potentially bad news. However, I would actually be quite happy to wrong about all this -- if anyone has found a solution for the OP, please post your solution here!
