WIP: achieving close to parity with Khronos' Sample Viewer in my model viewer (except I won't go as far as supporting extensions; the differences in the screenshot is I have one directional light going in the camera's forward direction while Khronos' uses a few point lights.)
The only model showcased in that doesn't come from Khronos' sample models is https://sketchfab.com/3d-models/ikea-lillabo-basic-train-set-c09d67bc0d804a1899b82079f836b934