I'm a rightie but bless/curse with cross dominance. I shoot long arms with my left and sidearms with my right.
Sticking with Armalite, you can choose the DBoys (cheaper) or VFC (expensive) PDW. They're both ambies.
If you happen to like long barrels, you can either get the complete KA SR16-e3 or just get the receiver. Those are hot.
Being an AEG, you'll most probably only needs the ambi mag release, which you can choose from G&P to Dboys aftermarket.
For fire mode selection, well you can try to shoot like Travis Haley and Chris Costa during their support side transition (grip position like a rightie's support hand placement when shooting thumb forward style on sidearm).
Sometimes it's those finer details that makes lefties felt left out. For example would be the swivel positions.
Again, AEGs like KA's SR16 has QD mounts on both sides.
Venturing into other makes, you'll have more options. Both MP5 and G36 is pretty ambies.
AK deserve special mentioning, as they're the only one (in AS world atleast) that have folding stocks to the left.