When you add a component via blueprint nodes, it won’t show up in the Add Component section, but it is still being added. You can test this yourself by getting the “Return Value” of the Add Component node, then calling the Get Owner function (retrieves the actor to which a component is attached), and printing it. It should print the name of your actor.
Similarly if you want to know which component is above your widget in the hierarchy, you can call Get Attach Parent instead of Get Owner.