10bit output from the mini monitor or similar PCIe or TB device is not really the most important part imho, the strengths of the mini monitor type device is it bypasses the graphics card output interfaces and therefore avoids any levels scaling and OS Level ICC colour management. Which needs to be ignored because Resolve doesn't use ICCs.
It requires 3D LUTs for final calibration of the display created sensing the patches sent to Resolves display output, if a ICC display profile is active in that chain then the 3D LUT calibration will be screwed up by the active ICC profile. Which is even more an issue on a mac. Also if the monitors are also used for applications that use ICC profiles for colour management, such as LR or PS the ICC (1D gamma curve part) can load at boot or login as normal for use with ICC based apps without affecting Resolve IF a mini monitor is used to bypass active ICC's.
Not directly related to dual monitor set up but there's also factors like insufficient screen refresh rate support from computer monitors or automatic switching between refresh rates depending on project settings which would be supported by a dedicated display fed from the mini monitor and native screen resolutions rather than scaling to fit the GUI. Many computer monitors lack sufficient hardware controls to correct RGB separation, grey scale and pull the display into rec709 before final calibration with the 3D Display LUT in Resolves Monitor LUT project options. Fine if the computer monitor is decent and calibrates well.
But it can be better to use a couple of cheap 20 - 22" monitors for the GUI fed by the graphics card and spend the money instead on a larger dedicated display fed by a mini monitor over hdmi, even a decent 32 - 42" LED TV as dedicated display if finances are tight, upgrade later.
More refresh rates are generally supported, generally better hardware calibration controls although screen uniformity can be an issue and onboard TV colour management can be pretty poor screwing with RGB separation unless picking a decent make and screen size large enough to more easily see noise in the image at native resolution with no scaling artifacts. After switching all the motion smoothing and noise reduction off.