Haven't seen any. I just use the index finger of my left hand to push the release forward and open the cylinder with the thumb of my right. I keep my speedloaders on the left side and hold the gun in my right hand with the thumb through the opening on the cylinder to hold it steady. I drop the speedloader into the cylinder with my left hand, twist the release (the thumb of the right hand keeps the cylinder from turning), wipe the loader off onto the ground, close the cylinder with the fingers of my right hand curled under the gun, placing the gun back in my left (firing hand). Takes less time to do it than talk about it.
Practice it and it will soon become second nature. Then you won't need a left handed gun. Right handed guns are much easier to sell anyway when you get tired of them.
Unfortunately we lefties have had to adapt to a right handed world so this isn't too big of a problem but it sure would be nice to have a few more options available. At least Ruger makes plenty of left handed rifles.
I didn't own a dedicated left-handed rifle until 1993. I've never owned a left-handed pistol. I learned to cope with the "regular" guns.
Savage has probably the largest number of left-handed models available. Followed by Ruger. Remington, Browning, and Winchester have been slowly adding left-hand specific models over the years, too. Today's auto-loading pistols seem to be moving towards ambidextrous controls, as well.