Getting WebGL to run on an Amazon EC2 server

Running OpenGL applications inside a virtual machine is very likely not going to perform well. First of all, you cannot use hardware acceleration but have to fall back to a software renderer. This is what the first error message tells you:

libGL error: failed to load driver: swrast

Installing the Nvidia driver does not help as there is no Nvidia card available - hence the second error message. Using a software renderer is possible, but it will be very slow.

So the answer is: Yes, it might be possible to do what you want but unless there is dedicated hardware that plays nicely with VNC on the virtual host this will not be a nice experience.