Voodoo linux drivers were open source IIRC. No firmware blob was required. The day nvidia bought 3dfx was very sad one for me.
1.: https://web.archive.org/web/20180220234020/https://www.openg...
2.: https://web.archive.org/web/20180629191415/http://www.opengl...
3.: https://web.archive.org/web/20180628125330/http://www.opengl...
I actually had some hope when nvidia bought it, but unfortunately, they killed the brand, only keeping "SLI", for something that isn't even SLI (scanline interleaving).
And yeah, open source drivers, but don't you find it annoying when you only get open source drivers for subpar hardware? It is unfortunately a recurring problem.