The link you reference seems more like a faux paper texture? The OP ‘riso noise’ is over the top but it seems to be a new hype and tells me they have never seen a riso print in real life, nor worked with one. Riso machines/drivers have multiple print settings, “Screen Covered” (bitmap/halftone), “Grain Touch” (the noisy dither used here) and special solid modes for vector line/text iirc.