How to activate experimental VR mode?

The code has been implemented ages ago, so how can I activate it?

I don’t get motion sick, and have a Quest 1 laying around, which is connected wirelessly via 5G router to my gaming PC with the actual rendering power.

I understand that it isn’t an officially supported feature, but I’d like to try it.

What’s the environmental protection rating of your headset? Cycling = Copious amounts of sweat.

The Quest lasted years of sweating in Beat Saber, BoxVR and The Thrill of fight.
Placing a box fan in front of me is sufficient to keep the lenses from fogging up in VZFit.
Besides, I don’t sweat that much anyway.