Okay, I got hold of a Raspberry Pi 3. There's now an experimental Gallium VC4 driver for the Broadcom VideoCore4 graphics chip in this device.
OpenArena runs perfectly as you might expect as it is a common test case and complete. Anyway, there was 0.A.D in the Raspbian repository, albeit an old version, so I thought why not give this a go?
It runs! At least through the menus, when you try to load a map it complains in the terminal about GL errors (this is with all effects disabled and quick and ugly water selected and closes.
Not bad though eh? The open source driver that I'm using here supports desktop OpenGL 2.1 according to glxinfo as well as OpenGL ES. However I believe the hardware does not support S3TC and only supports... EGL? Whatever the compression Android uses is.
Just thought I'd leave this here for someone to enjoy.
Kind regards.