Is it possible to change the font size of the numerics as shown in the screengrab?
You cannot change the size
Even with python?
What you could try is changing the background colour; give it more contrast.
I tried that. How can I change the background colour? I couldn’t find the setting for that.
User Preferences, Themes, 3Dview, Window background - last item in the color list.
Sadly that does not change the background color of the OGL window, but thanks anyway.