I am right-handed, and I tought myself to use my mouse with the left hand when working on my laptop.
The reason for that is that I have a couch, where the ottomane (the “long” part where you can rest your legs on) is attached to the right side (referenced to my seating position), meaning that, when sitting on this side of the couch, the arm rest of the ottomane is to my right side which doesn’t leave enough room to operate the mouse without obstruction.
The side left to me (where the rest of the couch is), is unobstructed and leaves enough room to place and operate the mouse there.
At first, it was hard to navigate with the non-domiant hand, and I used it for navigating within the web browser. The majority of mouse navigation in a browser is scrolling anyway.
After a just a few of weeks I noticed that handling the mouse with the left hand became more and more precisely. Now I use my left hand exclusively with the mouse. I even noticed that when doing stuff in Blender or Affinity for example, keyboard shortcuts are more accessible to me with the right hand when working with a laptop.
When at work however, I use the mouse with my dominant (right) hand, as the desk layout allows me to do that.
I hope so, that’s why the explanation is so detailed.