1. Final file format - .GLB (with Embedded textures).
  2. Model size:
    1. The final file size should be less than 30MB.
    2. The optimal size is 15MB
  3. Polygons count.
    1. Very important for app performance.
    2. Optimal - 35k, Maximum - 100k.
    3. The app can work even with more than 1M polygons but could cause poor performance on some devices.
  4. For best performance better to keep all textures in size of 1024x1024 px. ****2k textures are ok but don’t use bigger than that. Keep them in power of 2.

General 3D Model Requirements and best practices by Geenee: