Was OpenGL really the only issue ?
Probably not! (This is a good point, so thanks for pointing this out.) I didn't try much, but I assumed that the OpenGL 3D board was among the problems. I took one of the plain builds I had, I did not try to reconfigure and recompile.
However, I managed to get the broadway backend work with other desktop applications. I didn't test those much either, but at least I got the GUI displayed in the browser.