I mean it's basically inevitable that major hardware was going to be fairly dominated by big companies, just like how you're not going to find many small businesses producing regular ass non-vr monitors and the like, especially at the high end of things.

But overall, it's still a fairly diverse market. Beyond what you've mentioned, there's the valve index as easily the most major competitor. I've heard good things about pimax headsets, and they seem to be as close to a small business as the industry really can manage. Rumors say Sony is bringing psvr2 compatability to PC, which would be a huge advantage given the insanely cheap price tag for the quality. The apple vision exists, I guess, though it's locked in apples walled garden. The htc vive still seems to be around.