A:
Perhaps not going to answer your question precisely.
I am VERY left handed,
I learned from the beginning to use a mouse right handed.
So the Logitech trackballs I first knew years ago were also right handed.
Now...….. you CAN change the click switches and there are several.
However...…. again...… I learned to use my today M570 and its parents right handed.
I don't even realize I am using it, it has become a very fast and natural part of my (right) hand.
Good Luck!