Now,that depends (as you know) on a few things. Let’s just compare games like Neverball/NeverPutt versus
the Microcosm screensaver. You can play Neverball quite well even on a typical Hauku x86 laptop, but Microcosm requires a bit more muscle (aka HW-acceleration). Billard3D is ‘playable’ but still requires some HW-acceleration for smoothness.
As for drivers, you can have a OpenGL 4.x driver that fallbacks if the HW’s firmware doesn’t support a OpenGL feature. That is how you can have a unified OpenGL 4.6 driver for legacy hardware which can do software rendering if the hardware has limited features/no acceleration. OpenGL is all software - whether in hardware for acceleration or not. It is developed more like a client/server model just in driver/library (API) fashion.
2D graphics acceleration relates to this as well.
You’ll notice this when you see messages like “your hardware is too old for that…” or “your hardware is mighty, but your driver is weak - upgrade your driver”.