I'm mainly looking for e-ink devices.
I'm open to glowing screen devices, but in my experience, most are too reflective, and most are too bright.
This seems to be changing, at least for higher-end devices.
I don't know a way to test brightness, or test pulse-width modulation issues, but I think I need to get below 10 cd/m2, possibly down to 1 cd/m2. I am currently using a Benq monitor at 0% brightness, 30% contrast, 10% red, 20% green, 10% blue. Judging by the reviews here, Benq monitors range from 56 cd/m2 to 109 cd/m2 at 0% without further adjustments.
https://www.tftcentral.co.uk/reviews_index.htm
A long time ago I tried an iPad mini, it was too bright, and it's reportedly only 8 cd/m2.
https://www.phonearena.com/reviews/A...-Review_id3501
Many now go down to 1 cd/m2:
https://www.phonearena.com/phones/benchmarks#
However it's still hard to find comprehensive reviews and comparisons which take this into account.
P.S. It's possible that I've had more trouble with tablet screens because I held them closer than computer screens. So accounting for distance, 1 to 2.5 nits may appropriate.