I see I'm not the only one requesting this, but I'm disappointed to see that the previous request was from 2015, and seemingly not addressed.
Not having pen pressure support is a real mark against an otherwise excellent program.
It would be okay if at least I'd be able to just connect the tablet directly to the secondary (and not need Multiplicity to support pressure), but unfortunately, Multiplicity does not let go of the mouse pointer when using a directly connected drawing tablet on the secondary, so you end up with a functional but invisible pointer/brush, while the pointer graphic itself stays stationary (based on where the mouse was last)... so, kind of unusable, even with that attempt at a workaround.
I'm really hoping they (re)consider adding this feature, or at least allow the drawing tablet to be directly connected to the secondary, without having Multiplicity pin the pointer/brush graphic.