I've been a proponent of learning to work the pistol with one hand for a long time. Why? Of course, the obvious answer is Injury to one hand. Another, less obvious, but more common occurrence is situations where one hand is being used to perform a task such as opening a door or controlling/guiding someone.
Another aspect is confidence. Simply put, if you are confident manipulating the gun with your offhand, everything else is easy.
The basic gun skills are the same regardless of how many hands you get to use. They are Drawing, Shooting, Reloading and Addressing Stoppages.