I'm attempting to recreate this mask transparency effect I did in Procreate where it's not a perfect mask, and you can still somewhat see the masked object through the mask (pictured below).
Notice how you can still see the paper background texture inside the shape that masks the line. I want to give it the feeling of erasing the pencil stroke on the paper, but the stroke is still somewhat there since erasers on paper are not perfect.
I'm new to Grease Pencil, and I've managed to figure out how to get masks to work in general, but it's a TOTAL mask and not a partially transparent one. The closest attempt I've gotten is to have the mask shape be white with 0.7 alpha and "regular" blend mode on the layer, which does make the masked line somewhat visible like I wanted, but you can't see the paper background due to the white fill on the mask.
On the opposite end of the spectrum, using black as the color for the mask shape, 1.0 opacity, using "add" blend mode, this will allow the paper background to go through, but also completely mask the object (which is also not what I want).
Is there any way I can achieve the effect from Procreate in Blender Grease Pencil?