@Eskander sent. That should be all five squircles in 25% opacity white, identical at the pixel level (including margins) to the corresponding Suru squircle. So what you’ll see is all the pngs are in sizes like 256x256, 48x48, etc., but including some space around the edges or at the top/bottom. That should map exactly to the size, shape and position of the Suru icons in each of the five sizes.
EDIT: In terms of tinting the greyscale pngs, if that’s not achievable, then perhaps we could produce a greyscale version with no gradient across the main body of the squircle. In that case it would be a reduced number of colours. Possibly we could do a version with just four or five greys in total: one grey to stand for the main shade, another for the highlight at the top, and a couple of intermediate ones to allow antialiasing around the highlight Then the script could do the x -> y operation on those colours only, adding n brightness to the main shade to derive the others. I guess only experimenting would determine if that produces an attractive result.