"LuxVR" is a simple application that lets you change the brightness gamut on your VR headset, but unfortunately it's not maintained, has a lot of bugs, and probably just won't work. The developer wants your money, though.

Yep, the devs have their hand out for an eye watering $35 USD "donation" for this as you're expected to give them money for this by buying various completely empty DLC from Steam... digital panhandling. Like the homeless guys who splash dirty water on your windscreen at the traffic lights. No thanks.