Theres no reason really why they can’t use a BillboardGui for a system like this, it would make sense to use one if they are looking for a system which appears in the 3D world and isn’t locked to a specific surface.
You could use the ContextActionService to bind the ‘E’ key to interact with an element when the client is close enough.
You’d also need to look into the client/server boundary, and use RemoteEvents/RemoteFunctions to validate when the user has interacted and perform any server-sided code related to the action you want to happen.
Hope these articles from the developer hub help 