There are left handed ARs. I never went one, even though I shoot left handed. My rationale was that you never know when you will pick up another gun other than yours and most ARs will be right handed. While, I might be faster if I had a left handed gun, if I had to in an emergency pick up a right handed gun - would my old mind get confused and I would be killed on the street? (the street - humor).
I never had handgun problems as the Glock's grip angle and controls are easily manipulated with my forefinger. My 1911 has ambi safeties. Revolvers, not a problem. I supposed I might be slower by the millisecond demands of 'competition' but the slowness of my old age swaps that anyway.
Now, I have a Ruger PC 9mm carbine. I will shoot it in USPSA here (WNY) when the weather breaks. Can't shoot in in local IDPA as the nearest one doesn't not allow. However, should I reverse the controls or keep it rightie for the comparability issue with others of its ilk, if the Zombie apocalpyse hits. There were quite a few of the guns at the local gun show, so it seems popular.
I ran it RH in TX but I was more interested in running it than winning, esp. since a friend of mine was a PC state champion, so no way I would come close to that young fellow.
Thoughts - is the pick up issue real. In the service, you just adapted. BTW, I've tried to shoot RH with a long gun and it doesn't work. Practice you say - but now my right shoulder is a ruin (do to a car accident) and I am not putting impulses through it.