How to do a basic Point and Click Mechanic?

Hey, So I’ve just started working on a game, and I’m adding mechanics one at a time to a practice level to prototype it before I start building levels. So far the progress has been great, but now I need a mechanic that works like this:

The character is in first person view, with a small black circle in the center of the screen for reference. when he looks at an object that he can interact with, press E will come up on the hud and if he presses E (or any chosen button), the object will do something, like call an elevator or cause an explosion. In this specific case, I have a healing station that should tell my player’s health variable to go up by 2.

Now, at first glance, this seemed really easy to accomplish, especially compared to some of my other mechanics that were much more complex. However, after trying several methods, I cannot get it to work. I’ve looked at several youtube tutorials, but they are all very conditional, and I need this system to work for anything whenever I have line of vision and I press E on something. any thoughts? I don’t need the blueprint to be spelled out for me, I just need the concept or command that can send one variable from one blueprint to another. I looked at interfaces, but it doesn’t seem to be what I need.