Not reactOS "level", but rather in spirit. If Sony were to invest in a PS4-side implementation of the DirectX API the process of porting could end up being trivial.
Then again, Valve have already proven with their "togl" translation layer that even with the (allegedly minor) cost of translation, the performance gains of OpenGL not only eliminate that cost - but manage to beat native DirectX.
This Myth/lie continues to persevere.
a few facts about it. When Valve announced this, they also at the end, in "small letters" said that it was due to new improvements in the engine, and that these same improvements on the DX version would give the same performance boost on windows/directX, effectively making DX still faster. and another fact, this supposed higher performance has NEVER been actually shown and proven, certainly not on real users computers.
if you dual boot linux and windows and run one of their cross platforms games and measure performance, the windows version will still run faster and look better, despite this magical claim of higher OGL performance.