"Butterflies and fire" animation with particles effect and skybox. "Skybox" and butterflies are rendered by the same shader. 2 Skybox textures are generated in offscreen canvas2d. It is used for butterflies too :)
Tested on Oculus Go (with touchpad) and VR BOX2 (with joystick). For tests on a desktop (Windows 10 + Chrome) the "inline" webxr session and A,S,D,W,↑,↓ keys for navigation are used.
See also beautiful Effects Animation Butterfly.
WebXR samples     updated 28 Apr 2020