This app was mentioned in 2 comments, with an average of 2.00 upvotes
Yup, only one I've tried on android is HD model viewer: https://play.google.com/store/apps/details?id=com.dukedev.hdmodelviewer&hl=en
You could also host it on sketchfab and view it on your phone's browser
Just to make sure the problem was not the models I tried to view, I installed HD Model Viewer, which worked out of the box and has a file dialog to locate object files. This way I found out that a) the path /Android/data/com.hedgufu.modelviewer/files/ you gave in the description is wrong, it has to be hedgefu instead of hedgufu, and b) that the folder was actually created, but for some reason it doesn't show up in the Android File Transfer.app on my Mac.
So I had to move the obj files somewhere else and then move them with a file manager app on the phone into the proper folder. The next time I started your app the list of sample objects was replaced with a list of the model I copied to the phone. I could select it and was placed inside the model (a car). The auto-walk trigger wasn't visible, so I could not see the model from the outside. Tried several times, I get either auto-walk if I disable diorama, but no model, or in diorama the model, but no way to move out of it. I looked into some of your threads discussing 3d model viewer for cardboard, and obviously I am not the only one that ran into problems. Makes me wonder why you were surprised by the ratings you got.
Compared to this ordeal HD Model Viewer just worked, the interface sticks to typical conventions, so I could use it immediately, there is a useful help function explaining gestures and advanced features. I can select objects from wherever I want and it has a ton of settings. What's missing is stereo view, reading the gyro and a way to move without touching the screen. It currently has 611 ratings averaging to 4.2, and that is probably a fair rating.