I have been dealing with the small screen sizes of the Mac Mini when using screen share or remote desktop to administrate the Mac Mini servers.
With screen share I was also getting some bad black squares tracking the mouse pointer around.
I got the fit-pc HDMI dongle and it is great. The screen size is much larger and the overall quality is up. ScreenShare adaptive quality is pretty close to full quality. When using the dongle the GPU processes more of the display. With the dongle out it seems the CPU was handling most all of it. I used Intel Power Gadget to check this. I got one standard unit and one 4k unit. The 4k unit is physically smaller. I recommend this thing. I wish I did not wait so long to get them.