Not the first time Valve funded the development of FOSS drivers. They've already done so with Intel's Vulkan stack on Linux, AMD (AMDGPU) and Nvidia (NVK).
SteamOS's core functionality leans heavily on Mesa and there's been a lot of commits for the Adreno 750 lately, mostly coming from Linaro.
Fair enough. The problem is usually in terms of getting enough documentation and help to do this in a cost effective manner. If they manage to pull it off, I will start to second guess every phone OEM who seems to not go down this road.
SteamOS's core functionality leans heavily on Mesa and there's been a lot of commits for the Adreno 750 lately, mostly coming from Linaro.