OnePlus OxygenOS 13 vs Google Stock Android (Pixel UI) Comparison Thread. "Close to Stock Android". Not a Carbon Copy, but we're talking about Close to Stock Skin.

OxygenOS 13 vs Google Android Pixel UI - Animations

If this doesn't look "Close to Stock", I don't know what does. Most of you haven't even used OS13.. I've, and I can tell you guys it is the very close to Stock Pixel Skin. Again, Close ≠ Carbon Copy like Moto UI. Yes, there are Slight differences here and there.

If you're going to nitpick differences like OOS Now Playing Control Tile is different from Pixel UI, then even Motorola is using totally different icons and Personalisation Section.. Nothing OS is using totally different Quick Settings Panel and Lockscreen Design.