Ok got the 43" iiyama back on Monday, works this time and it's the repaired same one i sent back 5 weeks ago lol. HDR is a bit weird, if you only set it on on the OSD, it puts brightness to max and locks it, if you set it to on also in windows, it's a bit dimmer unless you fine tune the SDR a little, but no use having it use 50w more for desktop use. Sadly because it has HDMI 2.0, PS5 only benefits from 0.4ms response time, HDR at 4k60 isn't possible with full RGB range.
I've settled on 110% scaling because i'm not 25 anymore, might get used to 100% scaling but wouldn't risk it lol. Freesync work only up to 120hz, without it 144hz is fine. Sitting around 1m away, still have to get used to having to look around into the corners to see time and stuff.
Will see after a week or two if i'll keep it or sell it and buy a 32" dell for 100€ more or a 43" gigabyte for 200€ more. Would maybe like a brighter HDR and HDMI 2.1 for the PS5, but for 4K gaming it'll do i guess. Just need a card that does 144fps on AAA titles which might be a problem