True HDR and Dolby Vision kind of require at least the ability to make certain small areas very bright, so one could argue that 400 nits is fine in general, but then even the MacBooks go higher. The M2 Air has 500 nits and the Pro can go as high as 1600 I think. So, overall, certainly debatable what the threshold is or should be. For office use where spaces are very well lit, you certainly can’t get away with a dim screen, so that has to be kept in mind too.