That will be good to have the possibilty to create a texture from more than one image per channel. I means, add some imperfection in a second normal map that overlay the first. Also add some irregular pattern in a large texture mapping by overlaying images. A kind of photoshop layer system.
and blending like in UE → How to Paint Blend Materials in Unreal Engine 5 with Megascans landscape - YouTube
Thank you for you advice!