If I understand correctly, what you want is to have an event that does what your first blueprint did, but for a particular item that depends on which key you pressed, correct?
The way you could do that is: Instead of your Super Shotgun variable, you would have a Test Item variable and a Possible Items array. Every time you press a button, you set the test item variable to the value of one of the items of your array depending on which key you pressed (For example, the “E” key event would set test item to the value of get possible items index 3, and so on). So now know what item you are testing, and that changes every time you press a key.
You could even have a data table that saves the relation between every key code and the index of the item to be called, so that all of this happens in one event.
After Test Item is set, you would fire a second event (for organization sake) that would then test if Test Item is valid, if it is then if inventory contains Test Item, and then add it to your inventory.