The 3D Textured Mesh that Pix4D Desktop generates is not georeferenced. It has coordinates in a local coordinate system centered around the project.
Some external viewers permit you to add the offset of this file and place the 3D Textured Mesh at its correct position. If this is used, the 3D Textured Mesh will have the same precision as the mesh in the rayCloud of Pix4Dmapper.
The offset of the project is generated after step 1. Initial Processing. The project_name_offset.xyz file is stored in the params folder under: project_name\1_initial\params\project_name_offset.xyz
For more information about the params folder: What does the Output Params Folder contain?.
At the moment, only the .osgb and .slpk file formats are georeferenced.