I'm Nate, the one who posted in the forums. I started just asking if the feature existed, but was told I should ask for it as a feature so here I am. Hello :) First I wanted to say I love the program and find the features super useful. The powerstroke is one of the coolest features and I am having a lot of fun playing around with it. I have been an Adobe Illustrator for years but I am already enjoying inkscape more. Anyways, the reason I was asking about pressure sensitive line work is because it could be a huge time saver for manga art(or any extensive line art) where line work is incredibly important. It seems like all of the features actually exist in Inkscape, but not together as a tool. The calligraphy pen works nicely with pressure and the mass(for precision), but if the line needs to be edited in an meaningful way, they basically need to be redrawn.
The powerstroke feature is awesome, but in its current state may require a lot of manual setting line thicknesses if there are a lot of complicated lines. Being able to control the stroke width via pressure would make it a very smooth process. Unfortunately it would not be as useful without a preview as you draw. Maybe it could use the same preview the calligraphy tool uses? Even if that isn't a 100% representation of the final product, it would guide the user to understand how much pressure they are applying.
I asked about an auto simplify feature not only for the benefit of reducing the number of nodes, but also in aiding fast smoothed line work. I see that a line drawn with a pencil has a smoothing feature, maybe that can also be applied to the powerstroke outer lines as well; or maybe the pressure has an adjustable sample rate?
Additionally, it would be fantastic if there was a way to increase or decrease the relative distance of the powerstroke nodes from main path. In essence it would be like increasing or decreasing the width of the powerstroke. As an example I recorded my screen using a variable brush tool in Illustrator. It reads the pen pressure and applies it to the stroke, but also allows that stroke to be increases or decreased.
Screen capture example Video: https://youtu.be/u78JlGD9Y34
Example of the adobe brush tool simplify/fidelity options: https://youtu.be/iIW_oeUcO2E?t=144
That same tool in adobe also has settings to control/limit the brush size and shape. I've been utilizing mass, thinning and fixation to accomplish this effect in Inkscape.
I think that covers what I was originally asking about and more. Hopefully it was not too much. Thanks so much for all the hard work you have put into the program! I know this software is a lot of work and new features are no small thing. I am not really a programmer so I can't contribute to the effort that way, but if you have a need or desire to include a UX/UI designer I would be happy to help!
Manga line example that I did not draw:
If you got through the whole email, thanks for listening!
-Nate