Outliner as a Layer-System for Texture Paint, Sculpting and Masks

Before creating a complex new layer system you can maybe use the Outliner as a kind of.

As every object is of a specific type in Blender you could add a „Texture Object“ type as well.

Then every object type get a unique right click menu. E. g.

For a Texture opbject you may merge with layer below or above, set opacity, set blend mode, etc. just like in any graphic program.

For Sculpt objects you may boolean with another one, or remesh that specific object using a right click menu.

Also you it might be useable to group same object types in specific collections. This way you can nest layer/collections within each other. And you can give these collections also right click options refered to its including object type.