As somebody who just built an online WebGL-based chess web app (2D/3D voice controlled chess game with invisible pieces to practice blindfold), just wanted to chime in and say this is super cool!
Path tracing crushed my Mac M1 - around 8fps, but Rasterization Standard Quality performance was steady at around 30fps.
The camera controls were kind of driving me kind of crazy. I'd recommend adding a "Camera" button that toggles between three or four different views, something like Over the shoulder, Zoomed out, Zoomed In, and Top-Down.