Help on Constructing a grain filter

Hello! Hope you're having a wonderful day to whoever is reading this.

So I've been trying to construct a grain/dithering filter to soften gradients in photos and the such. I can get slight results in B&W, but I'm struggling in colour. There is an artist I adore for his style and warmth achieved through grain:
Nicholas Law

If anyone has any leads I should look into that would be much appreciated. I've tried using bomber to generate noise particles but the generation of it just for a preview takes a century to see or so it feels and none of the noise functions seem to be helping. So if anything, how would I generate the grain effeciently? Would it be best to learn to write a script for it?

Main Question:
Best way to generate a flat seamless noise/grain like print/white noise?

Update: I solved it X'D
2nd Update: I should have learned about noise distort much sooner ...