The output is either linear RGB in modern pipelines or unspecified probably-sRGB for older pipelines (which usually have wrong lighting math). It's the driver

The output is either linear RGB in modern pipelines or unspecified probably-sRGB for older pipelines (which usually have wrong lighting math). It's the driver that does the linear RGB to display space conversion when the engine swaps the render buffer. In the case of non-specified probably-sRGB color space I have no idea if it converts from sRGB to your display space, or if it just does nothing because it not specified.