Galco and Bianchi have been slow out of the starting gate to get into production for the 5" guns. Almost everything available now, and there are a lot of choices, are for the 4" guns and Galco's superb Ankle Glove holster is the only offering specifically for the Compact XD. The number of Left Hand offerings matches those for Right Hand. There is no shortage of leftie holsters.
We expect the lack of holsters for 3 and 5 inch guns to change in the future and we are constantly urging them to get into action on this.
Anything that fits a 4" gun will fit the 3" and the 5" except that you will have a protruding muzzle or extra space left at the muzzle but it should not affect the security of the fit.
Galco does make a synthetic (think Kydex) M7X Matrix belt slide holster that accomodates any length slide but it may not be the absolute best carry holster.