Interesting. Until it was mentioned in this thread, I'd never thought about whether the OK button should be on the left or the right based on the analogy of the order of pedals in a car. I learned the GUI in SunOs (UNIX) first, slightly before I encountered Windows. I don't remember which way round the OK and Cancel buttons were, but I don't think I had any problem accepting the order that they are in Windows. Now if I use Raspbian or Ubuntu, I have to make a conscious effort to click on the opposite one to the one I'd default to in Windows. Mind you, I've had about 30 years for the Windows way to get ingrained, and I'm now in my 50s rather that 20s - old dogs/new tricks.
The one thing that does not come naturally to me is using a left-handed mouse. I can use it as a pointing aid nearly as well with my left hand as my right, but the swapping of the buttons really throws me. My brain instinctively uses the left button for left-click, even though it's now my middle rather than index finger, and I have to stop and think that I must use the mirror image: still use index finger for left-click even though it's now the right button.
My mum, who is left-handed, uses her fork in her left hand and knife in right hand (probably she had to conform with the righties at school), and she has her mouse buttons the normal way round (though she holds the mouse with her left hand). She holds a pen in an exact mirror-image of the way I'd hold it, without resorting to the cack-handed way that many lefties do, which involves trying to contort the hand above the line of writing with the fingers and the pen pointing in the direction that a rightie would do. I can understand that a leftie has to take extra care not to smudge the line of writing if they are using a fountain pen, but that doesn't explain the very painful-looking contortions of the hand.