Ps4 uses Freebsd kernel, Then the kernel does not matter, no one will need to install drivers on SteamOS, the experience that Valve will create is the console.
SteamOS have to be compared with ps4 and xbone
And Android uses Linux as the kernel, then It all depends on Valve's work
Buy a Steam Machine when it is released, will be a competitor of traditional consoles, and will be much more powerful than the PS4 models, and will be guaranteed Lfd3, HL3 and several other games
And normal control sucks for FPS