Otherwise I think that the 32" at 495 chf (used as new) can be a good deal and I don't understand why
the 27 inch is more expensive than the 32 inch.

Hello,
my monitor is connected with the supplied DP cable which is 144 Hz. (it has both HDMI and DP cables supplied)
HDMI is limited to 100 HZ. (see amd monitor list under google then check freesync 2)
HDR is usable anyway. (to be seen for the usefulness of HDR, some people like it and others find it useless,
it's really a matter of taste)
My personal opinion on HDR is that without HDR it would be fine for me.
(I put it on depending on the game but there are some games where I find the image less pretty with HDR because it is less natural: it depends on the game)
If not I prefer the 32" (I tested both) but I got it in aktion at Digitec at 550 chf (that was the price at the beginning)

And also, what are the HDMI and DP versions needed for this 144Hz wqhd display with HDR?