Change line end style in Viewport (Pencil)

Hello,
I like to use the line style «pencil» viewport setup to extract drawings just monochrome as lines. Now I have a problem: I would like to use thicker lines (which works) but as soon as the lines get thicker, the line ends look terrible (they are just straight cut of at the ends which leads to really anoying cornering artefacts - see enclosed picture).
It is even worse with round stuff - there the segments tend to break apart and white spikes become visible…

Is there a way to use round line ends for this viewport setting? This would solve my problem imediately… or is there an other way of generating line art the way I would like to get it from a Rhino 3D File? I use Rhino 8 on mac by the way…