I'm finding it hard to find an actual 4k monitor with the HDR. Finding one with a HDMI 2.1 input seems rare. If you do find one there is considerable input lag. More common in the monitors are the 1440p, 144hz. Tv's are where I find a decent monitor but the smallest I found was a 55 inch with all the good specs. $2000.00 ballpark on those. I'm hoping something comes out about the time of the new console releases, but I may have to settle for the 1440p to get a smaller screen and low input lag.

4k PC monitors have been pretty meh. Unless you are willing to spend a lot of money for 4k, it's generally not worth it. Some are starting to be good such as https://www.engadget.com/lg-4k-ips-ultra-gear-gaming-monitor-104539945.html

But most are still fairly expensive. Eventually the prices will come down to something reasonable but for now, it's better to wait until 2021 before getting a 4k monitor.

I can't recommend any specifics for 4K, but here are some ones that popped up on Newegg, first 2 shipped from USA and 3rd from Ireland...
One has 1ms reponse (apparently when not using Freesync which I'm unsure how PS5 games will support), otherwise 5ms for the rest.
Site lets you filter by alot of factors (seems slightly different filters in "gaming monitor" section VS just "4k monitors" although content overlaps)

https://www.newegg.com/samsung-u28e590d-28/p/N82E16824022246?Item=9SIAN3GB8E5049
https://www.newegg.com/lg-27ul500-w-27-uhd/p/N82E16824025944?Item=9SIAN2HBVC7106
https://www.newegg.com/p/N82E16824025991

I may be wrong but I think those specs for those monitors are only attainable using the display port not the HDMI ports.  It does need to be HDMI 2.1 to achieve those specs with a console.

I see this monitor with HDMI 2.1 releasing later this year, the components seem good, but fair to wait for real reviews before ordering...
But probably ready by time you pick up a PS5... Actually, might be interesting if PS5/XSX also suppport Displayport...????

https://evedevices.com/pages/full-specs

https://www.tomshardware.com/news/eve-spectrum-gaming-monitors-ps5-xbox-series-x

I heard HRD on PC monitors isn't real HDR or something like that as well. So might want to check on that.

maybe a 1080p 23 inch monitor with 120hz+ and hdr + ips will do the job. if you want to stick with small monitors, I don't think you would see so much difference between 1080p vs 4k on small screen.

Assuming you're talking about a PS4 Pro because you're looking at 4K, you can still enable both Boost Mode and Supersampling on the Pro to improve framerate and image clarity, respectively (the system says that these can introduce some incompatibility, but I've never run into any issues with either). To be fair, Supersampling is only available on resolutions smaller than 4K (possibly only 1080p). Therefore, I only get to use this option when I play my Pro on my non-HDR 1080 screen, and, as a result, my sample size with this feature, in terms of glitches, isn't as large as my sample size with Boost Mode. Regardless, I have yet to need to turn it off, and I do think it can help quite a bit with games that support higher resolutions.

Googling the model number will usually yield some links for you. Also, you can usually find the manufacturer's manual as a .pdf, which will have a bit of detail on the specifications.

Regardless, this will give you at least some of the granularity you requested: https://www.rtings.com/tv/reviews/samsung/q50-q50r-qled