I’ve done several “flights” in hypobaric chambers, including a rapid decompression. Well worth it.
I’d like to see the sim at least have some sort of physiological feedback - it doesn’t need to be a tunnel vision/blackout thing, maybe just a menu that details your CO, hypoxia/SpO2, g-force, and temperature parameters throughout the flight. Give those environmental controls a reason to exist. Call it the “flight physiology” panel or something.
Though you could reduce color saturation at night with hypoxia effects. Or reduce night vision when you turn the cockpit lights up too high (or look into a landing light when on the ground)