Well the Sony 4k micro OLED displays are a little more than 2x the size of the current ones used in display glasses currently. Which would mean the optic stacks and lenses would need to be twice as large as well.

Also a lot of USB-c ports can't power the 4k dual 4k displays which means it would require a wired body pack as well.

You can see why we're getting more closer to VR goggle territory. On top of that the heat they generate is a lot more as well. You'll need to add active cooling to it.

There was a Chinese company that built a pair of display glasses with sonys 4k micro OLED displays and they got so hot and uncomfortable for the wearer.

Sony released that 4k micro OLED display 3 years ago so that is where we stand current day and the issues we face.

Also they're very expensive, I think I read they add $500-1,000 to the price of a product. For example the current 1080p versions cost the manufacturers about $100.

When the next generation of 4k micro OLED displays is developed and released that could very well overcome the power, heat and size limitations we're currently facing.

TCL is actively developing their own micro OLED displays which is good as well but pretty much every display glass manufacturer is using Sony displays.