I use procreate!
This is kinda weird but I use the same brush for sketch 1, sketch 2, lines, flats and shading lol... i have a special blender brush that's separate though.

i adore the 6b pencil, i have tweaked versions with streamline for lines and a bigger one I adjusted for flats/shading!
for quick rendering, i use a non-default blender brush i got for free online... forgot from where but I will post a link if I find it. I usually cell shade if I'm not feeling lazy and use this brush as an eraser to soften it a bit, airbrush probably has a similar effect

i also use the default flat brush for painting :)