Personally I'm excited for this on iOS—I find that reading boring stuff in dark mode at minimum brightness on my phone is easily the most effective way for me to fall asleep (contrary to the blue light/no phones in bed advice). With an OLED screen the amount of light emitted is so much lower than any alternative I've tried. For sites like HN (some threads on HN are pretty boring) that don't have a native dark mode, my solution has been setting up the "Accessibility Shortcut" feature to invert the colors on the screen. Three clicks on the lock button and the page inverts. It works okay, but it requires manual intervention for each site depending on whether it supports dark mode.