VR Mirror without distortion

How can I show picture on the PC output to fullscreen without distortion?
When I use console command “hmd mirror mode 2” I get distortion picture.

This demo works correctly and I want the same result:

I’ve been trying to do this for months, but the best I can do is create a screen output which has an aspect ratio similar to one eye. I think the ratio is 3:4, so you’ll want to create a window with that aspect ratio. Note that you’re not going to get “full screen” with this aspect ratio because monitors are usually 16:9 or 4:3. If you try to force it into the monitor aspect ratio, you’ll get the stretching distortion.

I’m just a noob at VR output though, so I’m sure one of the VR devs at epic has a real solution. I mean, they’ve gotta have one, right? If they go to shows with booths showing output on a full screen monitor, they’re doing something to do that…

I suppose anything that would render an aspect ratio wider than one eye would mean rendering more than you need for VR only, so you’d waste rendering resource and get lower frame rate than necessary.
If you are hacking the source maybe there’s a way to render one of the stereo pair cameras as full 16:9 and then pass on just the VR relevant bit to the part of the pipeline that applies the distortion and onward. Then you’d use that fullscreen sized texture to show on the monitor somehow.
This is just speculation as I have not tried anything like that but is sounds like it should be possible in theory. Not sure if it would add latency.