If you have multiple files for a single model such as obj / mtl/ textures etc. put all your files (such as model material textures etc.) in a single directory and compress it to create a single zip file for e.g. test.zip and upload this single zip file in the app to interact with the model. You can continue to upload single self contained files like fbx stl etc. if there are no extra files. So if more than one file for model zip and upload zip file if a single file upload the single file directly.

Important announcement :
After our last recent update some users have reported issues that the models are not getting loaded. This is most likely the issue due to some Android OS compatibility issues from 11 onwards as no such issues have been found on for e.g. Android 8. We are investigating this issue and will be fixed asap. Please do not provide bad rating and if you face this issue please send us a mail with your model at [email protected] and we will update you once the issue is fixed. You can most likely use it without any issue below Android 11 so if you really need for a while downgrade Android.
Android 3D model viewer with the following features.

1. Load 3D models in FBX Obj STL Glb Gltf formats
2. Rotate move zoom/scale models
3. Control light brightness
4. Control light orientation
5. Control the background color
6. Load animated FBX models and pause them

7. Premium version (HOLOFIL-X) supports Face tracking 3D animation export with payment

8. Supports upto 1M polygons
9. Might not work on some mobile phones (Please contact us if it does not)

Please send any feedback if you have (bugs / issues / 3d model files) to [email protected] to resolve the issues.

For the premium version HOLOFIL-X please check https://play.google.com/store/apps/details?id=com.Artosci.HOLOFIL_X

Visit www.holofil.com to see the 3D visualization product device that uses these apps with more functionality for interaction. A demo video of the interactive usage in the HOLOFIL device is here https://www.youtube.com/watch?v=JAbqc7LWdZM

You can use this sample 3D model in obj format to load to test the app https://tinyurl.com/yddxh3kp

for more free 3D models please check sites such as below for the formats below.
http://free3d.com
https://www.turbosquid.com/Search/Index.cfm?FuseAction=SEOTokenizeSearchURL&stgURlFragment=3D-Models/free
https://www.cgtrader.com/free-3d-models
https://sketchfab.com/store

Formats supported

OBJ/ MTL
FBX
STL
Glb
Gltf