I'd give the Huawei MateView 28.2" a 4/5.
I'd point out that here in the UK it's currently available for £450 and has been as low as £400 (including 20% tax) so as long as you don't go hunting for defects that you wouldn't otherwise notice its end-of-argument value for money, esp if you want a multi display setup. I've got two on my Mac Studio & I'm delighted (but note that to get two on a Mac Mini you'd have to run one at 50Hz via HDMI, but the difference between 50Hz and 60Hz is barely noticeable).
Maybe that calculator is designed for those who only have 20/20 vision
20/20, the original justification of "Retina" and, probably, the original LaserWriter resolution are
all connected to the same figure of 1 arc minute (0.00029 radians) as the typical acuity of the human eye based on tests like being able to see the gap in a nearly-circular letter C. That's an
angular resolution so (working in radians & assuming the gap is small c.f. the distance) it's the size of the gap divided by the distance. You can work back from that to calculate the smallest visible "gap" for a given viewing distance and then wave your hands and assume that gives you the minimum PPI for "no visible pixels". Double the viewing distance, halve the needed PPI.
At 12 inches (iPhone or printed page) 0.00029 x 12 = ~1/287 > 300ppi is "retina".
At 21" inches (desktop display) 0.00029 x 12 = ~1/164 so > 164ppi is "just" retina.
That was Apple's original justification for calling the iPhone display "retina" and all their other retina displays exceed the criteria - but ultimately its a marketing term and Apple can decide where or where not to stick it.
However, it is a huge,
huge hand wave that makes all sorts of simplifying assumptions about a complex subject - even before you get on to all of those people who's vision is either better or worse than 20/20, or second-guessing how close people are going to sit to their screens. You really don't want to get into too much "spurious precision" over whether a display is retina or not.
That said - on a 27" screen 5k
is better than 4k, but it's a lot of money for a small improvement. I think people who describe 4k as unusably blurry are being a
little bit precious - but it's their money.
I suspect the monitor is fine, but these surveillance experts can be incredibly clever.
Not having a significant portion of the national communications infrastructure depend on Huawei (or any other foreign manufacturer) kit is probably sensible, but putting spy devices in mass market electronics is a lot of risk for very little gain, and it's not like Huawei are the only made-in-China electronic goods we're using - not to mention respectable assembled-by-patriots-in-the-motherland kit with gaping security holes. If Beijing want personal data on Mx Average not-working-with-nuclear-secrets Person they can always just buy it from Google, Amazon, credit reference agencies etc. If you
are working on sensitive stuff it's probably a good idea to let your employers choose your kit...
So why are the MateView's USB-A ports advertised as USB 3?
Haven't tested it, but AFAIK they
are USB 3: If you use the separate MiniDP or HDMI inputs for video, you can connect the monitor's USB-C input to a USB 3 port on your computer and have it work as a USB 3 hub.
As for the original question:
If you are happy with a non-Apple display then I'd go with a M1 Mini and a display of your choice. If you prefer a high-PPI display, then the 24" iMac will probably give you the best quality display for the price. The Studio is good value for the power you get, but overkill for what you want, and its extra performance is very much dependent on a multi-threaded and/or GPU-heavy workload. I don't think there's any guarantee that the extra "longevity" will make up for the price difference.
The Studio Display is probably the optimum in display quality for any current Mac (ruling out the $6k Pro XDR) but it is hugely expensive.
Ideally wait for an upgraded Mac Mini but there is
absolutely no guarantee that one is coming anytime soon.