Transform specific vertices of primitive mesh/extra object using geometry nodes?

Question

I just started learning geometry nodes, and I have a question about manipulating specific vertices for meshes other than the original object that the geometry nodes modifier has been applied to.

Here's a node setup where I'm able to alter the X position of vertices on a plane object

From what I understand, this works because I created two vertex groups that become attributes that I can reference in the modifier.

However, am I still able to make specific-vertex adjustments to geometry that is not a part of the original object's mesh, such as a primitive or a separate object in the outliner?

Answer 1

EDIT:

I managed to achieve this effect by using the index nodes.

However, I still there's still probably a better way to specify a group of vertices using attributes

EDIT #2:

The named attribute node can retrieve attributes from other objects. I think this is the best way to do it. Thanks Markus