Well, technically it is not 5K display. It is half-5K, that has less pixels than 4K.
Display resolution nomenclature has gotten a bit weird, it's true. You're running up against the 5K barrier because it has 5120 pixels on the horizontal access, which technically makes it a 5K (5,000 pixel) monitor. Some people refer to ultra-wide displays as "5K2K" but because your vertical resolution is 1440 your monitor doesn't technically qualify for that terminology, either. 5K1.5K I suppose, although it doesn't matter enough to coin a new term; 5K2K already strikes me as being a bit silly.
Can I be sure that recent mac mini will support this resolution?
I looked at the monitor, itself, and I'm not certain. Here's why.
According to Apple's website, this is what we have for the Mac mini:
Support for the following combination of maximum concurrent display setups:
- Up to three displays:
- Two displays with 4096-by-2304 resolution at 60Hz connected via Thunderbolt 3 plus one display with 4096-by-2160 resolution at 60Hz connected via HDMI 2.0
- or
- Up to two displays:
- One display with 5120-by-2880 resolution at 60Hz connected via Thunderbolt 3 plus one display with 4096-by-2160 resolution at 60Hz connected via HDMI 2.0
Thunderbolt 3 digital video output supports
- Native DisplayPort output over USB-C
- Thunderbolt 2, DVI, and VGA output supported using adapters (sold separately)
HDMI 2.0 display video output
- Support for one display with 4096-by-2160 resolution at 60Hz
- DVI output using HDMI to DVI Adapter (sold separately)
In other words, the Mac mini is technically capable of powering a 5K display (which your "5K1.5K" falls under), but only through Thunderbolt 3... although there's mention of video output over USB-C, as well (which is the same physical connector as Thunderbolt 3). Your monitor has two HDMI connectors, which according to Apple would
not give you the full resolution, but it also seems to have a USB-C input. That's less standard on monitors at this time, so I can't really say if it would work, but it sounds like it should.
Looking on Amazon, there is one person who wrote a review remarking on troubles with a 2018 Macbook Pro, and it seems over HDMI. Resolution was limited to 4K for them until they bought SwitchResX. A software fix implies that either MacOS has trouble with that monitor and/or resolution, or that they're still not getting the native resolution but the software is upscaling for them.
I'd recommend trying to look up more about video over USB-C for monitors. Worst-case scenario you might just need to try it for yourself to see what happens. Apple does have a return policy; you could always make the purchase and, if it didn't work as you expected, return the system.