Adding Procedural noise to your renders in Photoshop

I strongly suggest you using a blur effect from the filter gallery to create noise, because it's more realistic in my opinion. You blur the gray layer and then apply field blur with any strength, then tweak the noise roughness, size and color. But I do prefer Add Grain from After Effects still, cause it's even better. Nice tutorial though, been doing that for years.

Instead of going around the houses making layers and changing blend modes - try this easier way!

Option-click the New Layer icon/Name Layer/Pick Overlay (from the mode menu)/Select Fill with Overlay-neutral colour) - OK

Now you have a layer that is named, filled with the perfect grey and I ready for the noise - You could make it into a smart object but TBH, there really isn't much of a time saving or need.

Its funny we try so hard to have a noise-free image when we render, and then we re-add the noise after in Photoshop.

have you tried adding noise and blur in fusion which has a more node based workflow?