Where can I find/how do I make a brush like the MyPaint pencil?

I’m obsessed with how easy it is to go from defined lines to diffuse shading with this brush. However the diffuse shading doesn’t look good when the brush is larger, making it harder to shade larger areas. Is there a way to modify/create a brush with this effect? Is there one out there?

What I want specifically is a brush that can go from defined when applying pressure, to an almost airbrush effect when applying less pressure

You could maybe try the SK3 pencils: https://www.youtube.com/watch?v=bPwozO7izbk

They’re the latest pencils made by Ramon, who made the MyPaint pencil, so maybe you can find some that feel right in there already. If not, Ramon would probably also be the person to ask about it.