Just purely from a PPD perspective a 5K Retina display will beat the Vision Pro, but from a readability standpoint I think they're equal. Like at "normal" text editor scales you can read everything just fine but a 5K display might be crisper.

What’s colour accuracy like? I wonder if the controlled environment with no external light etc could be useful for colour critical work.

Sorry, I haven't done any color critical work and am unsure of the specs.

If you're wondering about passthrough it's pretty good for most things but is definitely missing the dynamic range of the human eye, which no video camera or display can really match yet. Like a super bright light might just show up as white and you can look directly at it no problem. Basically the same as what you get when you record a video and watch it back on your phone.