Will Xbox Series X/S support HDR for 1440p or 1080p monitors that don't accept 4k UHD signals?

Microsoft locked hdr to 4k so if ur monitor dont accept 4k signals ( tick allow 4k box in settings must be selected for hdr) it doesnt work on 1080p 1440p displays usually only if they accept 4k signals. Because microsoft locked it since xbox one s and
one x. It is hard to understand why they not allow it now because they have xbox series s 1440p 120hz hdr console right?

Xbox only support hdr on 4k so we that have a xbox series s and 1080p 1440p hdr 120hz screen cannot get hdr because its not 4k. On ps4 it works tho 1080p hdr.

I'm wondering the same thing. I bought yesterday the asus VG27WQ1B. It's a 1440p 165hz curved monitor. My series x sees it as a 4k 60, 1440p 120, 1440p 60, 1080p 120 and 1080p 60 capable. Screen. If I select 4k and open the monitor osd, it shows 2160p 60. Even if I go to YouTube and open stats for nerds, the viewport shows 2160p. If I select 1440p 120 (the reason I bought it in the first place) and I go to calibrate hdr in the Xbox settings, the display automatically changes to 2160p 60 hdr on.

Definitely don't get no signal and like you said, "you wouldn't be able to activate a mode that your monitor doesn't support"

Did I accidentally just bought a monitor that has best of both worlds?

Does the 1080p support go for both the Series S and Series X, or just the Series S?

1080p is supported by both Series X / S,

However if your only playing at 1080p and have no plan's of upgrading to a 4K TV / Monitor, The Xbox Series S would be recommended as is a 1080p / 1440p gaming console and you would save £/$200, than getting the Series X, as that is a 4K gaming console and
you would never get to use the full potential of it if used on a 1080p TV / Monitor.

https://youtu.be/VIHny-XP8jM

Yes, I agree but as you said, I don't know why XB1X refuses to send HDR over 1080p or 1440p as it is now. If you force manual settings it makes you enable 4k before it'll enable HDR but in automatic settings I can click "enable HDR" and it still says "your
TV doesn't support HDR for games". All I can think is that somehow, some way, Xbox wasn't designed or engineered to output HDR through a non-4k signal. Since it's been like this for years I assume there is some sort of hardware limitation but I can't figure
out what that is.

I hope you're right, and I'd like to know the answer because that will affect whether I bother to upgrade or not.