What are some alternatives?
When comparing VR Sketch and Sketchfab Download API, you can also consider the following products
Tilt Brush by Google - Paint in spaces around you with Virtual Reality
MasterpieceVR - Powerful VR sculpting & painting tool
Oculus Medium - Sculpt, model and paint in virtual reality on a 3D canvas.
Insite VR - The easiest way to view your 3D models in VR
A-Painter - Paint in VR in your Browser
Poly by Google - Explore the world of 3D