While there aren't many backpack blowers made specifically for left-handed users, there are a few options you can try.
Some backpack blowers, like the Echo PB-580T and Stihl BG 86, have controls that can be used by either hand. They also have adjustable hip pads for comfort.
Another option is the RedMax EBZ7500, which has a hip throttle that can be converted from right-handed to left-handed operation.
If you can't find a suitable left-handed blower, there's the Next Level Engineering Lefty Blower Attachment. This kit lets you convert a right-handed blower to left-handed use.
As for workarounds, you could try practicing with a right-handed blower or consider using a handheld blower instead.
In the end, choose what works best for you based on your needs, budget, and yard size.