What parameters would that be? Make it look like Eastman Ektachrome High-Speed Daylight Film 7251 400D? For years, people have taken film negative onto telecines and created content of grain to be used as overlays. For years, colorists have come up with ways of simulating the color of specific film stocks by using reference film with test patterns that's been made available.
If a director/producer wants film grain added to their digital content, that's where it should be done in post. Not by some devs working for a streaming platform. The use of grain or not is a creative decision made by the creators of the work. That's where it should remain
1. Denoise the master, then add AV1 FGS metadata to tell players how to reconstruct the noise in the master (which is what the blog post is about) to get back the original image the director saw and approved
2. Do nothing (which is what they were doing), and let some of the noise get blurred or erased by the quantization step of the encoding process, or worse, burn shittons of coding bits trying to describe the exact noise in the frame, which hurts visual quality of the things people actually look at
All of these imply changes to the image that the director decided on to get around the underlying fact that deliberately adding noise to an image is, from a signal processing perspective, really stupid. But if we are going to do it, we can at least ensure it happens as far down the chain as possible so that Netflix's encoding doesn't destroy the noise. That's the idea you responded to: have the production company deliver a master with FGS metadata instead of baked-in film grain.