Over the type-C port they receive video, receive audio, receive power (<5W), transmit sensor data (accelerometers, orientation, etc), and receive commands such as switching to a 3-D display mode.

They're pretty great and I think the market segment will grow over the next few years.

One correction, the screens are actually located in the temple part of the glasses facing downwards, but they are reflected so they appear as if they are in front of your eyes.

They can do split-screen 3d, albeit at a lower refresh rate. When you put them into that mode they appear to the computer as one screen of double width.

I'm having trouble understanding the difference between this tech and the leading-edge AR tech like Meta's Orion glasses, which supposedly cost $10,000 to make

Why are these $500 and high-res enough to play games on? What's so much harder and costlier about the other AR glasses?

Well, AR glasses have cameras. Other than that I'm not really sure. I didn't even realize these had a 3D mode or other sensors, I thought they were just a pair of mirrored screens

Are these always-opaque where the "screens" are and only transparent (or not transparent?) elsewhere? If so, I bet it's the intermingling of transparency + overlaid pixels that's hard about the other ones

It sounds like the OP's ones have a button that switches between transparent, semi-transparent mode, and opaque.

I know a pair I've seen in the past was mostly transparent, but then it had an extra piece you could snap on that was just solid black plastic, kind of like a camera lens cover, and it would block out everything but the screens.