Another way can be to just integrate Unity as a web app, using the Web Browser 
I made a quick test with this game: http://www.tiny.vision/TinyRacing/TinyRacing.html which is probably a bit more complex than a 3D object renderer.
If you host this page on a local server on the machine, you can even send some commands to it through an API, and have the Unity app send local network triggers back to the Player.
EDIT: I found this tutorial online: Free Unity Model Viewer - YouTube
It contains source files to recompile. I don’t have Unity installed anymore and don’t really have the time to investigate these days (ISE is coming…), but by recompiling this project as a web app, hosting it on a local server and playing it through the web browser, you might have something working pretty easily.