Maybe this is to difficult as tech behind can be complex, but it is super quick & comfortable in zBrush.
With active Gizmo you CTRL click LMB plus drag to mask. Area behind your drag direction is masked and mask is blurred on release.
It searches for logical connections and make masking of a single finger easy.
In Nomad, I could imagine this behaviour when holding Gizmo button.
But there is a lot going on in background to make this a super smooth function in zBrush. Anyway, without asking……… 