[Quoth]

The issue with OLED and LCD seems to be people having the brightness set for outdoors and then not turning it to minimum. Set an old paperback under your night time reading light. Reduce the phone/tablet to same brightness as the page. Some can be turned cream/yellow/amber. Then there is no deleterious effect to your eyes.
Even auto light level screens are rubbish compared to manual. The issue is that auto, or manual, the screen doesn't have the same brightness as a book in the same lighting. An eink with the front light off is like a paperback, better than a 30 year old one, it is always matching the ambient light.

An eink with the front LEDs turned up high is as bad or worse than an OLED or LCD backlight. It's LED light ignoring the ambient level.

Also though many phone, laptop and tablet screen are shiny. You unconsciously focus on moving reflections and that causes a headache. Studies on CRTs facing windows with traffic or open plan offices showed this over 30 years ago. Have screen sideways to a window and never facing where people walk in an open plan office.