It's fairly simple to modify a sport rig to accept a chest-mounted reserve, making it legal wouldn't be easy because of the drop testing that would be required. The main container can be easily modified to accept two mains. The drawback with this solution is the reserve almost has to be a round canopy. Canopy manufacturer Performance Designs decided a few years ago that the only practical solution was to develop and TSO its own rig for intentional cutaways, one containing three ram-airs and other modern technology. The project hasn't been completed, however, and won't be anytime soon.
Skydivers have other options to in-air cutaways.
A suspended harness, of course, is a simple and very good way to learn emergency procedures. The simulator is programmed to present the jumper with images of malfunctioned mains that require different responses. This effectively keeps it out of the sport market, which may be the company's intention. I'm not a skydiver. A. A hook turn is a quick canopy turn performed near the ground.