Slightly off-topic, but the author also made gl4es, a library that basically allows all kinds of OpenGL apps to run on modern devices. Shameless plug: gl4es is what allowed me to port Neverball to the browser.
Neverball was working in the original glshim project before ptitseb forked it to gl4es. (Not to discount the significant work he's put in since, including the ES2 backend)
My bad, I completely forgot they worked off of a fork.
Did you ever try Neverball with glshim, though? Why? I'm the current maintainer of Neverball, always very interested in Neverball-related stuff.
When I was working on the Emscripten port, I tried a bunch of GL-to-OpenGL ES libraries. There were a few. I might have tried glshim, but not sure anymore, that was a couple of years ago. gl4es was the only one that worked without any obvious visual glitches.
I don't think there's a GL2ES and GL3ES? Are you thinking about GLES 2 and GLES 3? Those are graphics APIs standardized by Khronos, being versions of OpenGL for Embedded Systems (OpenGL ES).
https://neverball.github.io