ajz3d
I've made an interesting discovery today. It turns out that we can affect floating gnomon size in Display Options by turning off Guides → Guide sizes → Auto DPI Scale and then ramping up the scale to a much larger value.
The caveat is that it affects other guides, or from what I've observed, at least point guides and wireframe thickness. The former can be fixed by scaling down Point marker size from the same section of Display Options. As for the latter, I have no idea how to make the wireframe thinner.
So there you go. Still broken.
Thank you you saved the day. The wireframe can be thinned in Display > Geometry > Wireframe > Wire Width