Sorry, there isn’t.
The iOS viewer was a fairly simple and natural spin-off of the OS X Mac Rhino development process.
We looked at the Android development and it would be a much more difficult development process because of all the supported screen sizes and resolutions; none of which are managed by the operating system. In iOS all of the supported screens and resolutions are built into the development tools.
It would be possible for a third-party Android developer to use our free development tools and write one, but there are no plans for us to do one ourselves.