as you know MuiOWB from Fab is being ported and FF4.0 too (the latter even features WebGL) so feel confindent the web is covered.
Just as a precision, WebKit itself supports WebGL since 2009 or so. Enabling it in OWB would be possible, if the underlying GL layer offered all the needed bits (which it doesn't currently).
You are forgetting that full OpenGL support (including shaders) has been coming for AmigaOS4 really soon for years already, so even that is covered.