This is how blender does it
In the slot drop-down there is an icon showing the material and its name.
Blenders shader editor is always linked to the active object (world or style line), if no object is selected then it will be the last object that was.
If you want you could have a “dummy” object with only one slot and edit any material in the scene in the shader editor by flipping through materials with the material dropdown.
To explain a bit more.
Each object can have many material slots, each slot can be assigned to different faces of the mesh.
Once you have assigned different faces to each slot they will stay assigned (unless you delete the slot)
You can assign any material to a slot. You can even assign the same material to different slots of the same object.
In the shader editor under the “slot” dropdown you will see the materials that are assigned to each slot of the active object.
In the material dropdown you will see all the materials contained in your file.
To jump between the different materials of an object for editing use the SLOT dropdown to choose which material to edit.
To assign a different material to a slot (and its assigned geometry) use the MATERIAL dropdown.
If you do not ant to make a dummy object you can also add an extra slot to your active object without assigning any geometry to it.
Then in the shader editor you can use that slot to edit any material buy choosing that slot in the slot dropdown and flipping through the materials with the material dropdown.