I presume OneUp is the biggest player in this particular market
I think you’ll find that Shimano, SRAM & Campag might be slightly larger, and have deeper pockets.
EDIT: Brant, yes, you may well be right. Someone will have to design the equivalent of a chainring spider to get around that, or another means of avoiding flex.
aracer: any big sprocket could be described as extending the range, so yes they all do.